I dont understand whats going on with my engine

[5.0Torx]

Hey all

So last week at this time i had my battery go out on me. I got a jump, took it to AZ and got a new one. All was well, for a little while. Right when i started it up to leave the parking lot it ran fine for a few seconds and then the engine just died. I got it going again and let it idle for a minute and decided to get going again. Sure enough, 2 minutes later, 2k rpm, second gear, going uphill it starts bucking like crazy for about 5 seconds and then runs fine for the next few days. But the idle has been surging, ever since the new battery. I adjusted my TPS (might have been a little high, currently at .91ish) and pulled the battery cable today to reset the computer again. I drove it for about 20 miles right after reconnecting the battery and was very happy with it. 800 rpm rock solid, 19" of Hg at idle. I just drove it to campus to go study for a while and on the return trip it was back to surging on me. This is very frsutrating. On the old battery it would oscilate every now and then right at startup, but it would always sort itself out after like 5-10 seconds. I just dont get the feeling that my computer is getting along with these damn GT40Ps. It is much slower than stock, and now im having idle issues. I just dont get it and am getting very frustrated. Wheres the notorious foxbody MAF self-tuning-to-new-mods feature?

Sorry so long

Cliffs: new battery and now all of the sudden the idle is surging on me.

Any ideas?

 

[tannerc91gt]

Hey all

So last week at this time i had my battery go out on me. I got a jump, took it to AZ and got a new one. All was well, for a little while. Right when i started it up to leave the parking lot it ran fine for a few seconds and then the engine just died. I got it going again and let it idle for a minute and decided to get going again. Sure enough, 2 minutes later, 2k rpm, second gear, going uphill it starts bucking like crazy for about 5 seconds and then runs fine for the next few days. But the idle has been surging, ever since the new battery. I adjusted my TPS (might have been a little high, currently at .91ish) and pulled the battery cable today to reset the computer again. I drove it for about 20 miles right after reconnecting the battery and was very happy with it. 800 rpm rock solid, 19" of Hg at idle. I just drove it to campus to go study for a while and on the return trip it was back to surging on me. This is very frsutrating. On the old battery it would oscilate every now and then right at startup, but it would always sort itself out after like 5-10 seconds. I just dont get the feeling that my computer is getting along with these damn GT40Ps. It is much slower than stock, and now im having idle issues. I just dont get it and am getting very frustrated. Wheres the notorious foxbody MAF self-tuning-to-new-mods feature?

Sorry so long

Cliffs: new battery and now all of the sudden the idle is surging on me.

Any ideas?

have your alternator tested...

 

[Maryland Stang]

Check and pull the codes. It's not an issue with factory stock heads.

 

[jrichker]

See the "Surging Idle Checklist for help with all your idle/stall problems. Everything you need to find and fix idle problems is in there.

The first two posts contain all the updates to the fixes. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.

 

[5.0Torx]

Thanks. I am aware of the surging idle checklist but i just found it very odd that i would NOT have a surging idle problem on the old battery. How can changing a battery affect that so much?

I pulled the codes last weekend and cant remember exactly, but i remember getting 67 (had it in first gear during the test), 10, and 11. 11 is system pass, AFAIK, and 10 is meaningless.

Ill test again tomorrow i guess.

 

[v8only]

the computer doesn't know or care that the car has gt40p heads..that's not your problem

 

[liljoe07]

Posted via Mobile Device

Those codes are KOEO codes. You need the Engine Running codes.

 

[5.0Torx]

for KOER codes, do i just start it up and hit test on my little code reader?

 

[jrichker]

for KOER codes, do i just start it up and hit test on my little code reader?

Yes.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

 

[HISSIN50]

It's best to do KOER codes on a warm engine.