[sivart]

Everytime i get off the gas the exhaust will pop, like backfiring, so ive heard that it could be caused by running lean when off the throttle. So i trying to see if there is a vacuum leak somewhere....i have a boost guage off my other car and can hook it up to mine and see what it is. I have a lunati cam but i cant find the specs on it, but it is basically the same as the e303 cam.

[Stangzilla]

Originally Posted by sivart Everytime i get off the gas the exhaust will pop, like backfiring, so ive heard that it could be caused by running lean when off the throttle. So i trying to see if there is a vacuum leak somewhere....i have a boost guage off my other car and can hook it up to mine and see what it is. I have a lunati cam but i cant find the specs on it, but it is basically the same as the e303 cam.

A rich condition can also cause the same thing. But the only way to be sure is to have a wideband o2 then you will know if you are running lean or rich. You could also spend the money for a dyno but I think the wideband is a better investment. As fas as the vacuum thing leaks are never a good thing but exhaust popping can be caused by more than just that..

[sn94]

hey
i had sorta the same symptom
my car wouldnt idle correctly
and it was making the backfire,poping noise
clean the MAF, And The IAC
There is a neddle in your throttle body
release the neddle and screw it back to where it was
this made my car idle like a dream
any more help let me know

PaT #06

[ryans88gt]

To check for vacuum leaks, establish you base vacuum at idle. It should be somewhere around 16-18 in Hg. Rev the motor up to 2500 rpms and hold it there. You should see the vacuum drop initially and then increase 1-3 in Hg (to 20 or so). If the vacuum drops and stays down, you have a leak. You can spray throttle body cleaner around the gaskets while watching the vacuum to try to locate the leak.

However, I would guess that backfires in the exhaust are usually due to misfiring or an overly rich condition resulting in unburned fuel in the exhaust.

[sivart]

Originally Posted by sn94 hey i had sorta the same symptom my car wouldnt idle correctly and it was making the backfire,poping noise clean the MAF, And The IAC There is a neddle in your throttle body release the neddle and screw it back to where it was this made my car idle like a dream any more help let me know PaT #06

where is the needle at? is it in the butterfly valve? one of my friends has a timing light so im goin check/adjust my timing....at around 10*

[Stangzilla]

Originally Posted by sivart Originally Posted by sn94 hey i had sorta the same symptom my car wouldnt idle correctly and it was making the backfire,poping noise clean the MAF, And The IAC There is a neddle in your throttle body release the neddle and screw it back to where it was this made my car idle like a dream any more help let me know PaT #06 where is the needle at? is it in the butterfly valve? one of my friends has a timing light so im goin check/adjust my timing....at around 10*

Put the timing at like 14 degrees. You will notice a power difference. Run super unleaded..

[sivart]

Originally Posted by Stangzilla Originally Posted by sivart Originally Posted by sn94 hey i had sorta the same symptom my car wouldnt idle correctly and it was making the backfire,poping noise clean the MAF, And The IAC There is a neddle in your throttle body release the neddle and screw it back to where it was this made my car idle like a dream any more help let me know PaT #06 where is the needle at? is it in the butterfly valve? one of my friends has a timing light so im goin check/adjust my timing....at around 10* Put the timing at like 14 degrees. You will notice a power difference. Run super unleaded..

is it a big power difference between 10 to 14? cuz im running 87 now........if 93 is a noticable difference then i might just start runnin 93

[ryans88gt]

The power difference will come from the timing bump, not the fuel. The increased octane is just added protection against preignition, which is more likely with the timing bump.

Personally, my EFI car runs 15-16 degrees and I run 89 octane in it with no problems.

My carbed car runs 34 degrees total timing with the initial set at about 22-24 degrees and I run 93 in that car with 10.5:1 compression.

Really for a stock motor with 9:1 compression there is no reason to run anything other than 87 octane unless you notice preignition is a problem.

[Stangzilla]

Originally Posted by ryans88gt The power difference will come from the timing bump, not the fuel. The increased octane is just added protection against preignition, which is more likely with the timing bump. Personally, my EFI car runs 15-16 degrees and I run 89 octane in it with no problems. My carbed car runs 34 degrees total timing with the initial set at about 22-24 degrees and I run 93 in that car with 10.5:1 compression. Really for a stock motor with 9:1 compression there is no reason to run anything other than 87 octane unless you notice preignition is a problem.

OK what he said... Set your timing to 14-15 degrees take it for a ride and if it ride and if it pings put in super unleaded. Set the timing when you have a 1\4 tank or less so if it does ping a little you can go right to the station and fill up. Or if you have a full tank of regular just add octane boost..

[sivart]

Originally Posted by Stangzilla Originally Posted by ryans88gt The power difference will come from the timing bump, not the fuel. The increased octane is just added protection against preignition, which is more likely with the timing bump. Personally, my EFI car runs 15-16 degrees and I run 89 octane in it with no problems. My carbed car runs 34 degrees total timing with the initial set at about 22-24 degrees and I run 93 in that car with 10.5:1 compression. Really for a stock motor with 9:1 compression there is no reason to run anything other than 87 octane unless you notice preignition is a problem. OK what he said... Set your timing to 14-15 degrees take it for a ride and if it ride and if it pings put in super unleaded. Set the timing when you have a 1\4 tank or less so if it does ping a little you can go right to the station and fill up. Or if you have a full tank of regular just add octane boost..

thanks 4 the advice, ill try this either tomorrow or monday

[ryans88gt]

Check the plugs, don't just rely on your hearing to pick up detonation. Look at the plugs and compare to whatever you can find on-line for detonation. Little flecks (of aluminum) are BAD, rounded electrodes and grounding straps are also BAD. In general, you should be fine at 15 degrees, but better safe then sorry.

[sivart]

i just put new plugs in there, motocraft and set the gap at .050...i say put it at 14 and 93oct...but then again i dont want to pay for 93 gas prices.....

[hopper]

i had the exact same prob, and found my timeing to be to low, so i set it to 15 and cleaned out the air filter,, no probs now.

[sivart]

my timing was at 8 so i set it at 14 and it seamed to calm it down a little, im running 89 now. my filter is clean but it still backfire/pop but not as much. i have my spark gap at .050, should i leave it there? or is there something else i could check.

[ryans88gt]

That is a bit wide for the stock ignition I think. Could be causing a minor misfire, try .045 or 0.040.

[sivart]

Originally Posted by ryans88gt That is a bit wide for the stock ignition I think. Could be causing a minor misfire, try .045 or 0.040.

ok ill try that when i get home....

[TENGRAM]

.050 is ok. i keep mine a hair above that and have had them at .055 with no ill effects. the EFIs ignition is actually very good.

[Stangzilla]

Originally Posted by TENGRAM .050 is ok. i keep mine a hair above that and have had them at .055 with no ill effects. the EFIs ignition is actually very good.

Yeah generally it is but if he has some ignition parts that are on there way out or just worn his system might not give the intensity that the motor needs. I would go with the .040-.045 myself also..

[sivart]

Originally Posted by Stangzilla Originally Posted by TENGRAM .050 is ok. i keep mine a hair above that and have had them at .055 with no ill effects. the EFIs ignition is actually very good. Yeah generally it is but if he has some ignition parts that are on there way out or just worn his system might not give the intensity that the motor needs. I would go with the .040-.045 myself also..

you mean like cap and rotor? i think the guy b4 me changed it but i dont know how old it is. but i do have new plug wires and basically new plugs....havnt changed them yet,.....some stuff came up

[JBIGBOOTSY]

I made 23 in. of vac. with my mouth. All my buddies could only get 16-18.
I guess that means I have no vacuum leaks?