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Discussion Starter #1
Hey all. My apologies in advance for a long post, but its necessary. Recently my 88 mustang has begun to just randomly misfire whenever it wants to BUT only at IDLE. I'll run down a list of whats been done recently and what i know to be good.
New trickflow trak heat upper and lower intake, which i know for a fact is completely sealed w/ no vacuum leaks. Smoke tested and sprayed with carb cleaner to be sure.
New tune-up, platinum motorcraft plugs, ford racing wires, motorcraft cap and rotor.
New Summit racing 75mm egr plate.
New Trickflow 75mm Throttle Body.
Properly adjusted throttle position sensor to the neighborhood of .96-.98 volts.
1 year old iac valve which was cleaned during intake installation last weekend.
Recently replaced thermostat, which was originally a 160 race t-stat, back to a stock 192 t-stat.
Pulled codes, no codes found whatsoever.
EGR valve operating properly, even got it to act up with the valve disconnected from a vacuum source to ensure it was not the cause.
New fuel filter and wahlbro 255 lph fuel pump.
This all i know to be true at this time.


The car was running great, and i pulled out of a parking lot and got on it a bit and all of a sudden it was like a cylinder just dropped. I turned it off at the local gas station, started it back up and it was fine. Drove it around for a bit that night and it acted up at a stop very randomly. Sometimes it would be fine, other times it felt like a cylinder was just not there. So i decided well, the cap and rotor were looking nasty might as well do the tune-up. Replaced the cap rotor, plugs and wires and it seemed to be running much better.

Drove it around a few days and just tonight im on my way home sitting in traffic and all of a sudden it feels like a cylinder has one big miss and than it levels out. A few seconds later, another big miss and it levels out. Again a few seconds later it felt like 3 or 4 good misses in a row and than the idle raised slightly on its own and never did it again. Got it home and sat there at idle in drive for about 30 minutes and all of sudden there it is again. A good hard miss and than it would level out for a few seconds, miss again, level out, and finally miss like 4-5 times the idle would raise and than it was gone. I'm literally pulling my hair out over this problem.

My personal thoughts at this point. Possibly because i changed back to a regular thermostat temperature has become an issue on some component. I'm thinking that possibly the ignition module on the side of the distributor is maybe getting tooo hot and intermittantly giving out a poor signal. I have never seen one that only caused a miss and not just flat out killed the car though. My other thought is, well maybe by some coincidence the coil is getting weak, but from what i have experienced ignition missfires generally occur under load, and this car runs smooth as glass at anything above 1500 rpm.

I do appreciate any advise, and again i apologize for the length but i wanted to be thorough. Any ideas or things i should check before i go out and buy a new distributor and a new coil would be greatly appreciated, as i do not wish to spend anymore money on this car this year unless necessary. Thank you all again for your help.
 

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how do the plugs look? timing? It doesnt have **** to do with the cooling system
 

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oh yeah plat plugs are for fags throw some autolite 25s in it, copper plugs
 

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Discussion Starter #4
Plugs actually looked pretty good, slight bit of tan on the electrode from the old ones but other than that looked good. Timing is set up right now at 10 btdc, it was at 16 for a long time but i set it back down to ensure that wasn't causing a problem.
 

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does it clear up when you advance it? balancer mighta spun
 

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Discussion Starter #6
it does clear up considerably as i hit the gas, and when the timing is up past like 20 ish. I thought only the sn95 series stangs had issues with the balancer spinning, but if thats the case maybe i should replace it. Now that you mention it when it was doing its random miss thing at idle i was able to give it a little brake torque to raise the idle to like 1k and the miss went away completely.
 

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just keep advancing it, if it clears up then its bad. Because the light is flashing at 20 doesnt mean the timings at 20. Make the bitch ping then back it down
 

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Discussion Starter #8
Thanks for the advice, its getting late here and my neighbors will rip me a new one for staring and running the car, i will get back to you tomorrow if it gets better. Thank you again!
 

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**** them I said its ok, a wise phaggot once taught me

drive car
bump dizzy lil bit advance
drive car
bump dizzy
keep doin till it pings
bump other way

ignore the light
 

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when you say the balance may have spun, what do you mean ? isn't there a key way that locks it in place ? I don't get it, please explain
 

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balancer is 2 pieces, the front part is basically a big ring, **** can move
 

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Oh....are you talking about stalk balancer with the rubber in between the the two metal rings ? So i take it that this isn't really an issue with a one piece balancer ?
 

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One cylinder misfiring should not cause a big stumble and the rpms to jump back up when it stops acting up. Short of attaching a bunch of noid lights to everything and waiting for it to happen, you might have to start guessing or wait until whatever fails completely. It never hurts to replace the PIP sensor inside the dizzy and the TFI module but that might not be the problem.
 

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Discussion Starter #14
I replaced the balancer and it had spun slightly, but only by like 2 degrees of timing. i reset the timing back to what i had it at b4, which was between 16-18 degrees which is good for me because i use 93 anyways. It still does that random missfire after sitting for a little while at idle, where like it just cuts out an than comes back. I was actually thinking about replacing the distributor as an assembly, which would be much easier considering it comes with teh PIP and TFI module usually. Should i even bother with a performance one or just nab a stocker from like napa or something?
 

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Discussion Starter #15 (Edited)
UPDATE: I have recently replaced a few more parts on the old misfiring mustang and problems still continue. Moving forward i have recently replaced the:

Distributor-replaced with a direct replacement MSD ready to run pro billet distributor
Coil- replaced with a direct replacement Street Fire (Subsidy of MSD) Coil

The misfire has evolved as far as im concerned. The misfire has become drastically MORE noticable. Upon replacement of the distributor the misfire has moved into the 2500 ish rpm range. I literally cannot accelerate the RPMs over 2500 as the engine begins to cut out almost as though its at a rev limiter. It does not matter if the engine is under load or if i just rev it up in neutral it cuts out almost completely at like 2500 rpms.

THoughts: i'm personally wondering if maybe something isn't wrong with the new MSD distributor. I've seen a few horror stories about MSD stuff where ignition boxes fail, and essentially the little module on the side of the distributor is an ignition module so I'm going to try to get an exchange from MSD. My other thought, is that well maybe one of the cats is clogged and revving it up doesn't allow the exhaust to escape and thats whats causing the misfire. At work tomorrow I'm going to try and get it up on the rack and pull out both O2 sensors and try to rev it up to see if it gets any better to eliminate the cats. I'm also going to try and reinstall the old distributor and see if the problem goes back to just the random misfire at idle or if the high rpm misfire remains.

Final Thought: I HIGHLY DOUBT it but, i was wondering if maybe the new Trick Flow manifold is allowing too much air into the engine and the stock exhaust manifolds are not allowing enough air out?

Sorry for the extreme length but i'm trying to get out everything i know right now, I'm trying to get the thing track ready for Sat, but at this rate i'll be lucky if i can even get it to and from work its getting so damn bad! Thanks again everyone.

Edit: I'm also going to try and do the salt and pepper shaker repair as well, with expanding the terminals to get the better connection as well. Don't know if this has anything to do with this particular kind of problem, but i will let everyone know if anything changes or if i figure anything else out. In the meantime let me know if anyone has anymore ideas as to what else might be the problem! THANKS!
 

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I am having the same issue and can not figure this thing out. except haven't changed out the distributor.
I am getting ready to just drop it off at the shop and tell them to get it right.
 

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did you check your fuel pressure ?....maybe the fuel pump is going out
 

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Pull your ECU apart and take a look at the circuit board right under the capacitors. If you see little black blobs of goo under them, your computer is shot. Either replace it, or the caps with the same replacement ones.
 

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Discussion Starter #19
UPDATE again: I pulled the old distributor out and the old one back in. Problem solved for now. Something inside of the BRAND NEW MSD distributor was cutting out above 2500 rpms causing erratic spark loss. Sent out the new one to be replaced and when i put the 2nd new in ill let everyone know if the problem continues or if it was indeed a bad distributor. As a side note i did check fuel pressure and it was right at running spec so i know thats good. I like the idea of checking out the internals of the ecu though, might just do that as a check to make sure everything in there is looking good. I was thinking about putting a chip in and i might check the comp out at that time but i dunno yet. will keep u all updated.
 

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I know this may sound simple and stupid but check your firinig order, sounds like you may have a plug wire crossed. just a thought
 
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