3800 Misfire going after shifting into 3rd..

[jk99gtp]

I was coming back on I-88 last night, and decided to go WOT out of a tollbooth since the weather was cool and wanted to see what she had.

Car ran freakn awesome in 1st, and 2nd, shifted into 3rd about 90-91mph and the car started making popcorn noises under the hood and was accelerating horribly! I immediately let off the gas and took it easy the rest of the way home..I did not get an SES or flashing SES for that matter.

Any ideas why this happened? The LAST thing I have done is changing the plugs from AC Delco 41-932 to Autolite 605's gapped to .056-.057. I reused my wires when I changed the plugs out (They were AC Delco's that had like 2 to 3,000 miles on them.). I did have a hardtime trying to get those suckers off when I was changing the plugs, so maybe there is a possibility the wires were damaged? I am going to Murrays to pick me up a new set today to see if this was the case. Glad Im getting my Autotap this week so I'll be able to see whats up if it still continues....

My mods are as follows:

3.4"
Thrasher CAI
1.9 Gen 3 rockers
DHP
U-bend delete

Thanks for any suggestions,

Joel
'99 GTP

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[beyerch]

that gap is way to high IMHO. I'd consider going .045 - .050 range. I'm guessing it was lean and was missing. Sometimes the stock plugs get damaged when doing a plug change as well. Do you happen to have any log data ?

 

[rob]

I gap all these colder plugs less aswell. These ignitions are hot but I was always told "the colder the plug the less gap you should run". Preventing premature fauling or I guess in thi instance A missfire. It sore of sounded like you were experiencing some KR..

 

[Mike K]

Joel,

I had the exact same thing happen to me. I limped the car home on 5 cylinder and popped the hood only to discover the number 5 plug wire came off the coil.

 

[alexgtp]

Joel. Need to atap it.

MAke sure which cylinder it is.

Are the rockers making any banging noises? Hopefully a rocker did not come loose..

 

[sweetness]

my guess: either plug wires, or no di-electric grease. I am leaning towards #2. If you didn't put di-electric grease on the porcelin (sp?) part of the plugs then that is what happened. I fought with the same problem for 4 weeks before sticking some grease on there. Ran perfectly from then on. The first few runs on the new plugs without the grese were just fine, then the same thing happened to me at the end of 2nd gear. POP POP POP POP POP.... i bet you have a cracked plug.

BC
h34r:

 

[jk99gtp]

hey guys,

Thanks for all the replies. No sounds of clacking or anything that would indicate a loose rocker, car runs totally fine with normal driving. Still even getting excellent gas mileage...

Here is the deal. I swapped out the wires and basically drowned them in di-electric grease, thought it might had been the number 6 plug wire since the bracket fell out and the wire was sorta touching the o2 sensor. Put everything back together and took her out for a spin...

Unfortunately it still exists, here is what is happening:

Performance shift off - Floor it, car runs great, runs through the gears without any problems.

Performance shift on - Floor it, car runs great through the rpms, when it gets ready to shift it starts hesitating for a sec and then goes into the next gear. Then thats when all the hell breaks loose, it sounds like Im having machine gun fire in my motor (makes a rat-tat-tat noise). If I let off the gas and get on it again, its totally fine again, until of course it shifts into the next gear.

Alex or anyone for that matter, is this symptoms of valve float? I mean, if it was misfiring and all it would do it throughout the whole rpm range. Which it isnt cause it runs freakn awesome until it gets ready to shift into the next gear.

I do have a DHP, which brings the shift points up a bit.

If this is valve float. Alex you have any time in the upcoming weeks to do a spring install? Let me know..

Thanks for all your help guys. I should have my ATAP in a couple of days and will run a scan to get some logs...

Joel
'99 GTP

 

[alexgtp]

Sounds like massive misfires.
if it is a machine gun sound. Did your ses light start flashing? and than shut off?

 

[jk99gtp]

Originally posted by alexgtp@May 18 2004, 10:48 AM
Sounds like massive misfires.
if it is a machine gun sound. Did your ses light start flashing? and than shut off?

Hey Alex,

I am not throwing an SES or flashing one for that matter.

I am thinking this might be valve float, as I can totally get on the car with the performance shift off and its totally fine!!

What is the best springs I could get? I was thinking of calling around and looking to see if I could get a set of LS6 springs. What else would I need if I were to purchase these?

Thanks,

Joel