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Discussion Starter #1
Im copying a few posts I have on sn95forums for more exposure. Ive been having some issues lately with my 02 gt and would like some input from you guys.

This is a loaded post so be prepared for a lot of reading. So it all started maybe a year ago where I started getting an exhaust leak and got lean codes for bank 1. I kept tightening it but I later found that the nut on the manifold flange is stuck halfway down the stud so it wont sit flush. I used a hose clamp to temporarily fix it. In the meantime I noticed that the idle sits around 1200 rpms and stays there and I got a slight misfire. Well one day it all of a sudden started idling like crap misfiring like crazy. I have been datalogging and all I see out of whack are bank 1 is pulling a lot of fuel (its running super rich) and the fuel pressure is anywhere from 2-10psi. But sometimes it will sit at 45-50psi and when I was poking around today I noticed the tps isnt putting out any voltage and unplugging it and the iac do nothing. Its weird because sometimes itll run horribly and have low fuel pressure and other times itll run better but have really high fuel pressure.

Ive unplugged the frps and attemped to start it but it wont start. Also it seems that unplugging the vac line does nothing. Also throttle tip in, lugging the motor and stepping on the gas (or any quick changes in throttle position) will cause misfiring.

I cant find a common issue with any of this except maybe a fried ecu.

Here are a list of codes its throwing
P0102, P0113, P0190, P0301, P0302, P0316, P1132, P1152 and P1506. Ill have to check again because I think its throwing more codes now. A few of them are from me unplugging things to diagnose the issue. Any thoughts or where to start?

From another post

I installed a spare iac I had lying around earlier for shits and giggles. It immediately ran perfectly and even stepped down from high idle like its supposed to. I even blipped the gas and she responded right away. Then I took her out for a spin and the same throttle tip in and wot miss came back. After I got back I let her idle and it was missing but not as bad as before. It seems that the iac was part of the problem anyway and I think its heat related. Nothing seems out of the ordinary in the datalogs, even the fuel pressure and trims were fine.

Any ideas?
 

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6 Cylinduh, Really Bruh?
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I'm going to state the obvious, revert to similar issues I've had, and offer suggestions. Some of this may sound like I'm talking at you like a new guy to the scene which I know you aren't so don't take offense.

First and foremost clear the codes. Erase everything because we need a clean slate of codes to work with. With codes showing up due to items you tweaked to trouble shoot, it's made it that much harder to troubleshoot.

Now we have a clean computer memory. Now, drive the car. Drive it or idle it or whatever til those codes come back. Ensure everything is put back the way it needs to be prior to drive and idling and all that jazz.

My initial thoughts are the IAC is bad. A bad iac will cause the car to mis and get pissed off to the point of you'll be driving down the road and the car will start missing like crazy until it eventually dies and you'll have it start it over and over and limp it to an auto parts store. It's happened to me on my explorer and my mustang.

Next ensure the hose going from the cold air intake to the iac is undamaged. We are dealing with 16 year old plastic and rubber here. This will also cause misfires. I've seen YouTube videos of guys disconnecting this tube at the IAC to make it sound like it has cams. I've read not to drive it like that for fear of damage but they would let it idle and do that. I personally hose clamped that hose in 4 spots. Cai connection. Hose to the plastic box. Plastic box to next hose. That last hose to the IAC. It was loose as all hell and not making a proper seal.

Next to that TPS not working. Honestly I don't know a whole hell of a lot about that think except it needs to sit at .8 to 1 volt at idle I believe. Constant. If it can't do that replace it.

Clean MAF. Always helps.

Check for vacuum leaks. With the the of my car I'm a fan of inspecting all vacuum lines and if it's cracked replace it. If it's not hose clamp it because the rubber is so worn out it expands and loses it ability to make a good seal without clamps.

Your fuel issue could be related to the iac or tps. They are failing send the ecu the wrong value of air and it's dumping or reserving fuel to compensate. I don't know any experience with fuel issues so I really can't help all that much. All I've done in the past is had my injectors cleaned and reflowed.

What would I do? Get a motorcraft IAC off amazon. Install it and reset the computer. Take it out and see what happens. Trouble shoot from there.
 

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Discussion Starter #3
I'm going to state the obvious, revert to similar issues I've had, and offer suggestions. Some of this may sound like I'm talking at you like a new guy to the scene which I know you aren't so don't take offense.

First and foremost clear the codes. Erase everything because we need a clean slate of codes to work with. With codes showing up due to items you tweaked to trouble shoot, it's made it that much harder to troubleshoot.

Now we have a clean computer memory. Now, drive the car. Drive it or idle it or whatever til those codes come back. Ensure everything is put back the way it needs to be prior to drive and idling and all that jazz.

My initial thoughts are the IAC is bad. A bad iac will cause the car to mis and get pissed off to the point of you'll be driving down the road and the car will start missing like crazy until it eventually dies and you'll have it start it over and over and limp it to an auto parts store. It's happened to me on my explorer and my mustang.

Next ensure the hose going from the cold air intake to the iac is undamaged. We are dealing with 16 year old plastic and rubber here. This will also cause misfires. I've seen YouTube videos of guys disconnecting this tube at the IAC to make it sound like it has cams. I've read not to drive it like that for fear of damage but they would let it idle and do that. I personally hose clamped that hose in 4 spots. Cai connection. Hose to the plastic box. Plastic box to next hose. That last hose to the IAC. It was loose as all hell and not making a proper seal.

Next to that TPS not working. Honestly I don't know a whole hell of a lot about that think except it needs to sit at .8 to 1 volt at idle I believe. Constant. If it can't do that replace it.

Clean MAF. Always helps.

Check for vacuum leaks. With the the of my car I'm a fan of inspecting all vacuum lines and if it's cracked replace it. If it's not hose clamp it because the rubber is so worn out it expands and loses it ability to make a good seal without clamps.

Your fuel issue could be related to the iac or tps. They are failing send the ecu the wrong value of air and it's dumping or reserving fuel to compensate. I don't know any experience with fuel issues so I really can't help all that much. All I've done in the past is had my injectors cleaned and reflowed.

What would I do? Get a motorcraft IAC off amazon. Install it and reset the computer. Take it out and see what happens. Trouble shoot from there.
Any help is appreciated. Ill clear the codes today and do an idle relearn. Im suspecting the cops are failing, though its a stretch since both banks are misfiring. Ill try to find a set from my old 00 gt I have stashed away somewhere.

I sprayed around some carb cleaner everywhere yesterday and watched the fuel trims which were unaffected leading me to believe its not a vacuum issue. Im still not ruling out the intake to head gaskets though. I see some dried crud near some of the cops, perhaps from leaking gaskets.

Its possible my spare iac is failing too. Ill look into getting a new one. And the tps seems to be fine. Datalogging shows its registering the correct values. I must not have been making contact with the pins when I backprobed the sensor last time. Ill have to clean the maf too since it sits a lot and is probably dirty.

The fuel trims are better now. Pressure stays steady at 40psi but the ltft stays at about +12 for both banks so the ecu is correcting for a lean condition. Maf issues usually manifest themselves this way.

One cool way to test for both a bad maf and post maf vacuum leaks is to unplug the maf. The ecu uses tables like speed density does and relys on the o2 sensors to keep the fuel trims in line. Ive used this method to diagnose issues on my vic before. Its interesting how well it runs with the maf unplugged lol. You could even run it with no intake tubing if you wanted. That would rule out leaks in the intake tract anyway.

Thanks for the input!
 

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Over the years I have had idle problems caused by the TB butterfly valve, the MAF, the IAC and the COPs. I've never had a problem with the TPS.

Almost immediately after buying the car in 2006 I put on a new BBK TB/plenum. The car started sputtering and dying at stop signs and going around corners. The idle would surge up and down before dying. It ran fine when it was cold and the motor was in high idle. It only started running rough and dying when the car warmed up and went to low idle. The IAC requires a certain amount of by-pass air around the butterfly valve to work properly. The new TB butterfly valve was closing too tight and not giving the IAC enough time to stabilize. I opened the butterfly valve a little by adjusting the TB stop screw and the problem was solved. By the way, wear and tear on the stock TB stop screw can also cause that same problem.

Five or six years ago during a huge rain storm I drove through some very deep water. Water splashed over the windshield. Water came in under the doors. It also splashed into the engine compartment where it was sucked up by the CAI. Water went through the supercharger, through the intercooler and fouled the MAF. The car wouldn't accelerate, every time I pressed down on the throttle it was cough, sputter and almost die. Let up on the throttle and it would run. The MAF couldn't sense the increase airflow so the ECM wasn't adding any fuel. Cleaning the MAF solved the problem. I was lucky that the head unit and intercooler stopped most of the water. A guy south of me hydrolocked his motor.

A couple of years ago, the car wasn't idling correctly. I know that people say it won't work but I've done it and it worked on my car. I was still running the original IAC so I took it off to look at it. It was filthy inside. Black carbon deposits everywhere causing it to stick. I cleaned all of the crap out of it with carb cleaner and q-tips and it started working again.

I've had other problems where I just took it to a shop to get fixed. I had one COP go bad. It did not throw a code. The engine just missed at high rpm. They found the bad COP and replaced it. And I killed another when my intake manifold broke and I sprayed coolant everywhere. If you replace your COPs stay OEM. The aftermarket ones are not as good.

By the way, except for the two newer COPs, my COPs, MAF and IAC are all original. I do have an ever so slight miss that comes and goes. I'm thinking that after 17 1/2 years I ought to change the boots on the COPs. Rubber deteriorates.
 

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Discussion Starter #5
Over the years I have had idle problems caused by the TB butterfly valve, the MAF, the IAC and the COPs. I've never had a problem with the TPS.

Almost immediately after buying the car in 2006 I put on a new BBK TB/plenum. The car started sputtering and dying at stop signs and going around corners. The idle would surge up and down before dying. It ran fine when it was cold and the motor was in high idle. It only started running rough and dying when the car warmed up and went to low idle. The IAC requires a certain amount of by-pass air around the butterfly valve to work properly. The new TB butterfly valve was closing too tight and not giving the IAC enough time to stabilize. I opened the butterfly valve a little by adjusting the TB stop screw and the problem was solved. By the way, wear and tear on the stock TB stop screw can also cause that same problem.

Five or six years ago during a huge rain storm I drove through some very deep water. Water splashed over the windshield. Water came in under the doors. It also splashed into the engine compartment where it was sucked up by the CAI. Water went through the supercharger, through the intercooler and fouled the MAF. The car wouldn't accelerate, every time I pressed down on the throttle it was cough, sputter and almost die. Let up on the throttle and it would run. The MAF couldn't sense the increase airflow so the ECM wasn't adding any fuel. Cleaning the MAF solved the problem. I was lucky that the head unit and intercooler stopped most of the water. A guy south of me hydrolocked his motor.

A couple of years ago, the car wasn't idling correctly. I know that people say it won't work but I've done it and it worked on my car. I was still running the original IAC so I took it off to look at it. It was filthy inside. Black carbon deposits everywhere causing it to stick. I cleaned all of the crap out of it with carb cleaner and q-tips and it started working again.

I've had other problems where I just took it to a shop to get fixed. I had one COP go bad. It did not throw a code. The engine just missed at high rpm. They found the bad COP and replaced it. And I killed another when my intake manifold broke and I sprayed coolant everywhere. If you replace your COPs stay OEM. The aftermarket ones are not as good.

By the way, except for the two newer COPs, my COPs, MAF and IAC are all original. I do have an ever so slight miss that comes and goes. I'm thinking that after 17 1/2 years I ought to change the boots on the COPs. Rubber deteriorates.
I have a 75mm tb but its been adjusted ever since I started getting a hanging idle so Im pretty confident thats not it.

I was thinking maf too but its responding to changes in throttle angle and seems to be reporting the right voltage. Ill clean the iac thats on it and the oem one just to rule them out.

I hate to spend the money on new cops since this pretty much came out of nowhere, not how cops usually fail anyway but it is still possible.

Im stumped, literally nothing is out of the ordinary in the datalogs and nothing changes from when it runs fine to when it starts misfiring like crazy. Ill start the car and itll idle fine and respond to throttle input but as soon as I drive it and put a load on the engine itll start misfiring. This is quite an odd problem. Maybe the ckp is going out? Ill have to do more googling and poking around.

Oh and I cleared the codes and reset the kam to no avail.
 

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6 Cylinduh, Really Bruh?
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Post the codes up once they start popping. They will at least guide you to what is going on.

Cops do fail overtime. If you're in a pinch eBay is super cheap and will get you by til you can afford some good ones. I want to say like 40 bucks for all 8. If you want take the plunge and replace them with eBay specials. If the issue goes away at least you know.

Here you go. 28$ shipped with 5 star rating. Like I said pure diagnosis stand point.

https://www.ebay.com/ulk/itm/252223...252Fulk%252Fitm%252F252223798318%26rvr_id%3D0
 

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Discussion Starter #7
No codes have popped up yet but I noticed its temperature related. Im thinking coils could be bad but I also noticed bank 2 stft and ltft are a lot higher than bank 1 which would be indicative of a vacuum leak on that bank yet I cant find one. And thats the side thats not leaking at the manifold to x pipe connection. I think Ill reseat the exhaust and try new coils but I dont think either will fix it.
 

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Discussion Starter #8
While Im waiting for my new coils to come in I thought Id pull a few plugs. I pulled the coil on cylinder 5 and was greeted by coolant. I pulled all the cops on the drivers side and 5-7 were up to the top of the plug. I cant believe it would even idle like this! Now its just a matter of getting that crap out of there.

On a side note Ive noticed dried coolant on that head for a while now but didnt really think of it. Is it possible that the gasket for that head is leaking somewhere?
 

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6 Cylinduh, Really Bruh?
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While Im waiting for my new coils to come in I thought Id pull a few plugs. I pulled the coil on cylinder 5 and was greeted by coolant. I pulled all the cops on the drivers side and 5-7 were up to the top of the plug. I cant believe it would even idle like this! Now its just a matter of getting that crap out of there.

On a side note Ive noticed dried coolant on that head for a while now but didnt really think of it. Is it possible that the gasket for that head is leaking somewhere?
There's no way your motor could even run if there was that much coolant inside each chamber. Have you pulled the plugs and looked inside? If you're lucky the intake manifold to block gasket is leaking filling up the coil holes. Can you trace a leak anywhere? Look in the coolant reservoir. Is there oil in there? Take the oil cap off, is there a milk shake looking substance there or is it just oil?

I hope it's not a head gasket. That would totally suck.
 

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Discussion Starter #11
While Im waiting for my new coils to come in I thought Id pull a few plugs. I pulled the coil on cylinder 5 and was greeted by coolant. I pulled all the cops on the drivers side and 5-7 were up to the top of the plug. I cant believe it would even idle like this! Now its just a matter of getting that crap out of there.

On a side note Ive noticed dried coolant on that head for a while now but didnt really think of it. Is it possible that the gasket for that head is leaking somewhere?
There's no way your motor could even run if there was that much coolant inside each chamber. Have you pulled the plugs and looked inside? If you're lucky the intake manifold to block gasket is leaking filling up the coil holes. Can you trace a leak anywhere? Look in the coolant reservoir. Is there oil in there? Take the oil cap off, is there a milk shake looking substance there or is it just oil?

I hope it's not a head gasket. That would totally suck.
I doubt its the head gasket, I meant the intake manifold to head gasket. Im guessing that bank 2 leaked probably around the coolant passage towards the front of the head and leaked towards the back of the head. That would explain why 5-7 are full. Im sure the cylinders are dry its just the spark plug wells filling from the top. Im going to borrow a shop vac from a friend tomorrow and suck up all that crap. Im not touching the spark plugs until I dry out the wells. Im still surprised it ran as well as it did with the spark plugs being completely submerged lol.

Not too long after I bought the car I pulled the cops and it was the same story but way less coolant. It sat before I bought it allowing the gaskets to shrink. The past year or so it sat when I put my vic on the road to commute to and from ft myers for the academy to not put miles on it. Im getting all the issues sorted out before I put it back on the road but it looks like letting it sit again has allowed the gaskets to shrink again. I bought new gaskets but Im going to clean up and retorque the intake before I replace the gaskets.
 

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6 Cylinduh, Really Bruh?
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Ah ok that makes way more sense now.

If it helps when I did my Intake manifold I used fel pro gaskets and copper rtv around the coolant ports. I did this twice (once on a Dorman which I promptly removed and second on the FRPP I have on now). To this day no issues.

Just because I'm OCD and wouldn't want to risk killing new COPS I would replace the gaskets and the intake manifold. I wouldn't be shocked to find a crack in the manifold somewhere because after all it's plastic sitting ontop of a hot ass engine. Again that's me talking.

Good call on shop vacing before removing plugs. Might want to replace those plugs while you're at it. Again that's me talking. No telling if it affected the plugs somehow. For 30ish bucks cheap insurance. Again i get ocd on repairs. I hate doing things twice and gives me better peace of mind.
 

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Discussion Starter #13
I just bought fel pro gaskets off rockauto last night though Im not sure Ill be installing them right away or not. If my intake it cracked its got to be a hairline crack on the bottom somewhere. When I do the gaskets Ill pull the intake and inspect it with a fine tooth comb. Ive read of others having hairline cracks that only affected it or leaked when hot.

And to be fair I read that vacuum trick on google lol. Someone else had the same problem and didnt have shop air like me so he rigged up something to get it out of there.

Good call on the plugs. Ill inspect them for sure before I put it all together. They dont have many miles on them and actually looked really good when I bought the car. Ive put maybe 3k miles on the car since I bought it. I dont know if coolant can harm spark plugs physically so I should look into that.
 

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Discussion Starter #14
To wrap this up, I cleanup up the head and sucked up all the coolant with a wet dry vac and installed the new coils. She runs like new again! Other than having to mess with the iac one more time shes good to go.

On a side note, you cannot set the base idle with the iac unplugged on this car for some strange reason. Ill put it back to where it was and maybe the idle wont hang we’ll see.
 

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Discussion Starter #15
Welp today the misfire came back with a vengence. It ran ok for a couple minutes then developed a constant miss. I took it down the street and it got worse and worse to where any amount of throttle would make it miss and sputter and eventually it would die. It would crank over and over again maybe run for a second and die. I had to push it the rest of the way home. Its throwing codes P0190, P0460 and B1204. Im thinking either frps or fpdm.
 
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