stumble bad at idle.

[kraus]

Helping a friend out on her t. She drove home yesterday after driving car all day running fine. Hit the highway and a plug wire fell off at plug. Put wire back on started car missing runs horrible. Pulled all plugs all look normal tanish brown.

Checked fuel pressure 40 with vaccum does not move when removing vaccum. Boost gauge is irradatic at idle. O2 mvs in 900 at idle on scanmaster. Replaced o2 same reading in 900. Tried resetting computer same issues. Tps is 40 ,unplugged maf tried restarting to run any better off then plugged in.

So where to go next...

 

[whitehot1]

What plug wires is she using that just fall off the plug while driving? I just have to know this.

Post all the scanmaster numbers with the car warmed up to normal operating temps at idle.

Is the boost gauge a compound gauge that also shows engine vacuum. If yes what is the engine vac. at idle?

Sounds like there is a vacuum leak. How old are the vac. hoses?

 

[kraus]

Ac delco wires. Engine vac is between 4 and 6 bouncing around like said. Vaccum lines are new.

She was driving down highway with her son got caught in rain. Webt to slow up on on ramp and it ran like crap. Called me told him check all lines hoses etc. He found plug wire on rear driver off. Plugged back in and since runs like poo. Like said pulled all plugs, and changed o2. No difference. I will have to run back over there and get scanmaster readings.

 

[kraus]

02 929-890
Af 04-06
L8 35-46
Bat 13.2
Int 128
Bl 123
Clt 167
Ats 97
Rpm 950
Tps 40
Iac 37
Cc 19
This is at idle

02 929 960
Af 10
L8 59-72
Bat 13.2
Int 128
Bl 123
Clt 167
Ats 100
Rpm 920
Tps 40
Iac 76
Cc 97
This is in gear ifle

 

[whitehot1]

I wonder since this happened when being caught in the rain. Perhaps the connector plugs going to the ECM may have gotten wet?

O2 is reading high,Iac valve is higher than should be but not terrible, i like it around 20-25 others like it 15-20. TPS is a little low, should be .42 key on engine off.

That plug wire coming off like that is strangely weird,perhaps it's time for some new plug wires. Autozone Bosch premium spark plug wires are good and cost around $30.00 with a lifetime warranty.

You could try starting the engine and unplugging the cam sensor to see if it runs better,the engine will stay running like that. But once you turn the engine off you will have to plug the cam sensor back in to restart it,the engine won't start with the cam sensor unplugged.

Even though the MAF sensor is reading in spec,you could unplug it to see if it runs better,perhaps it got wet from the rain.

 

[kraus]

Ive tried both of them no difference. I noticed fuel pressure gauge does not go up or down even giving throttle. It stays locked at 40.

 

[kraus]

Im wondering if module or something got wet and its all out of wack

 

[whitehot1]

What is strange is the o2 readings staying as high as they are at idle. They should be bouncing all over the place. But you said the spark plugs looked normal when pulled. And the BLM's are within spec and look normal.

At idle, with a closed loop chip, the 02s bounce around between 000 and 800 mv

 

[whitehot1]

Im wondering if module or something got wet and its all out of wack

You can have the ignition module tested at Autozone free of charge.

You will have to separate the coil from the module for them to test it though.

 

[whitehot1]

Here is a link for troubleshooting info that may help with this problem.

http://ihadav8.com/forum/VortexBuicks/engine_starts_but_does_not_run_p.htm

 

[whitehot1]

Ive tried both of them no difference. I noticed fuel pressure gauge does not go up or down even giving throttle. It stays locked at 40.

Helping a friend out on her t. She drove home yesterday after driving car all day running fine. Hit the highway and a plug wire fell off at plug. Put wire back on started car missing runs horrible. Pulled all plugs all look normal tanish brown.

Checked fuel pressure 40 with vaccum does not move when removing vaccum. Boost gauge is irradatic at idle. O2 mvs in 900 at idle on scanmaster. Replaced o2 same reading in 900. Tried resetting computer same issues. Tps is 40 ,unplugged maf tried restarting to run any better off then plugged in.

So where to go next...

Do you have another fuel pressure reg. you can swap out?

 

[gsgnnut]

Not a believer in coincidence the problem is either rain related or that plug wire is damaged. Any chance the maf got wet? Also # 1 idle problem is vac leak our Maf air leak

 

[VtheGNMan]

Did she recently change the plug wires where maybe it wasn't secured that well in the 1st place? Are all the plug wires going the correct cylinders? If they were off and driven that way it can burn the coil/s out. If water somehow got between the coil pack and the module underneath it could short out one or the other or both.

 

[kraus]

Anybody else got any ideas...

 

[kraus]

No regulator to swap, I have another coul and module I will try that and see.

 

[kraus]

Shes been driving it everyday zero issues. Drove 45 minutes to track, got rained out. Drove home , they stopped to eat and when coming off ramp like said started missing like crazy. Pulled over found wire off , reconnected and has run like crap since.

 

[kraus]

Im going to try my spare module, coil, and wires. See if solves anything. Also new set plugs. Ordered a regulator also.

 

[whitehot1]

Did you read and follow the troubleshooting steps in the link i posted above from vortexbuicks-etc.com

To find this problem your going to have to go step by step in a troubleshooting tree or guide and eliminate them from being the cause.

Unfortunately this happens sometimes and can't pinpoint the cause easily.

 

[kraus]

Swapped out module, coil ,plugs, and wires. Cleaned throttlebody, iac ,,checked maf, all intercooler connections.
After all this o2s are reading 250 350 idle it up and jump around to 600 700 ish. Let idle down back to 250 350 ish again. Blm is 115 at idle now,Fuel pressure gauge is locked at 40 psi no matter what do, even giving it throttle.
Ordered another regulator and see. I checked all the grounds, even disconnected battery for 15 minutes just in case something just stuck.

 

[Bescurred]

Vac should be more than 4-6

I bet you have a really bad vac leak...is it idling really high?