Engine Missing under load.

[scaldwellk]

I have a 92 Talon TSI with a strange problem. When I am driving a give it throttle it seems to have a stutter type miss. I had the engine all rebuilt at 104k and it now has 115k on it. I put in a new O2 and a B16g turbo this month. I took it on to the interstate highway and hit what seemed to be a wall. When I got it up to about 75 to 80 mph it made a shutter as if you drive over a wake me up bumps at 30 or 40 mph. At this speed It would not go when I pressed the throttle, but just shutter. If I slowly gave it gas it would slowly gain speed, but not go if it seen boost to the engine. Today on the way to work I gave it full thottle in 2nd gear and went to 3rd. When it boosted it was as if the car shut down and then came back to life after boost droped. I am only boosting stock pressure.

One thing I was thinking, but was unsure, is that it could be the fuel pump going bad?
Any input on this would be great. thanks.

 

[WeaselHack]

Check your base timing just to be safe but sounds like it could be a boost leak. My friend had the exact same symptoms in his 91 but was in denial about it being a timing issue. Borrowed a timing light and well...what do you know...way off. Hope this helps.

 

[talnteddriver29]

Definitely pressurize the intake system and post your results. My bets on a boost leak.

Hope that cures the problem

 

[1990talon]

Agreed check timing and do a boost leak test then post.

 

[andymoraitis]

In addition to the advice you received above, I'd also make sure that you pick up a logger to see what's happening under boost. While misfires are usually related to either spark or fuel, a failing TPS can also cause similar symptoms. From a diagnostic standpoint:

1. Boost leak test
2. Verify base timing at 5 degrees BTDC
3. Verify correct plugs (NGK BPR 6ES or Autolite 63) at .028 gap
4. Verify fuel voltage to the pump
5. Check/replace plug wires
6. Replace fuel filter
7. Buy a logger and log a 3rd gear pull

It would also be great if you updated your profile.

Keep us posted,

Andy

 

[scaldwellk]

Sorry, but I could not get on the site for some reason?.

I drove the car to work today and it seemed to run fine, even under boost. This made me think, could I have a bad BOV that sticks after boost? Is there a way to check if the BOV is bad. It is the stock unit.

 

[WeaselHack]

The missing issues i had before fixing my boost leak were intermittent. I guess its possible that your BOV is sticking but very unlikely. You can however test it while you are performing the boost leak test by disconnecting the vaccume line to your BOV and using a tire pump (or similar) to trigger the valve and listen as the pressure is vented.

Try the list andy provided above and let us know how it works out. Take his advise and get a datalogger - very cheap and provides usefull infromation in troubleshooting these types of issues. Good luck!

 

[me612]

New plugs/wires. Make sure you gap the plugs.

 

[PSI NRG]

Check the wires for small holes if theres even the smallest hole they will arch and cause the plug not to fire you can tell if they have holes if you see white makes on any of the rubber.

 

[scaldwellk]

BOV is sticking from time to time. Also found out that I was Hitting fuel cut out. Stepping the car up to a 2nd gen MAF and some 550 injectors. I had a friend look at the car and found it to be the same issue he had with his once.

Thanks for all the help everyone.