87 GN Problems

[Fat Kid]

For the last few months I've had the following two problems, perhaps related, but probably not.

1) The car usually hesitates or bucks when partial throttle is applied. This typically happens more often when the car has not been driven for several days or is not warm, but seems to occur at any time. In addition, sometimes the RPMs will drop and the engine will seem almost ready to die when the throttle is applied fairly vigorously from a stop. It will then flare up, proceeding as normal afterwards.

2) Boost is creeping up and top end performance is poor. The wastegate hose also habitually falls off and is taking a beating every time it falls off.

Yesterday I replaced the wires and plugs, as well as the O2 sensor. On the initial drive afterwards, the car died after one 3/4 throttle application in 2nd gear, and also did some bucking/hesitating. Any ideas/suggestions?

Thanks!

 

[BLACK6PACK]

First of all, put zip ties on the wastegate hose or you'll blow the motor.

Do you have a scan tool such as a scanmaster, direct scan or turbolink? If not, that would be the first thing to buy. Without sensor readings its hard to tell. Could be a bad MAF, could be the IAC or TPS is out of whack, too many things could be wrong and without sensor readings we're shooting in the dark.

 

[NASSTY]

Do you have a spare coilpack to try on the car?Or a TR buddy that has a known good coilpack you can try?That's where I'd look first.And for the hose that keeps falling off I'd get a new wastegate Y hose.You can overboost if it falls off and that could hurt your engine.

 

[Fat Kid]

Wow, such quick replies. Sorry for not including my signature in the original post, it will probably help you understand my position more.

Scanmaster readings are all normal. I have the TPS set at .44 at idle, and just replaced it about 5 months ago. IAC is also set within normal parameters, and no malfunction codes or anything of that sort.

Unfortunately, I don't have any TB friends in the area, so coil pack testing isn't an option. At this point, I'm seriously considering just ordering one and trying it to see.

I'm going to see if I can't get a new Y-hose and some zip ties ASAP. The current hose is just a mess.

Thanks for the input!

 

[Fat Kid]

No ideas?

 

[WIKEDV6]

Check all the hoses for cracks and things repalce them if you have to and zip tie them , especially the one on the side of the turbo to the WG. how much boost are you running? how old is the fuel filter?mass air flow readings? The IC hoses, are they loose or partially off? How is the hose between the mass air flow and the turbo? any tears or openings? What is the fuel pressure? need more info.

Goodluck
Prasad

 

[Fat Kid]

Other than the Wastegate y-hose, all the hoses are in good condition. The IC hoses are all connected and zipped. The fuel filter is new, MAF is 07 at idle. The boost is stock, 14#, and the FP is stock (43#, I believe). The MAF hose is in good shape as well.

Thanks for the input!

 

[scottyb]

Chip?
My hesitation was horrible with the stock, better with Red Armstrong, better with Thrasher. Still not perfect, especially cold. With the stock chip, it would usually stall on first cold start.
Replace your wastegate hoses.

 

[WIKEDV6]

Fix the WG hose, replace the hose and zip tie them first. how high does the boost creep at the top end?

 

[Fat Kid]

I don't think it's the chip, as it was fine for several years before and I haven't changed the chip. I don't want to put in the Thrasher when the car's not running well either.

I'm not sure how high the boost creeps as when I go over 9# or so of boost I get over 10* of knock. And the knock is not from bad gas, it has been happening since the WG problems started. I will replace the hose soon, but I don't think that's the problem either.

When the wastegate problems started I heard a loud crunch and then a pop. I got over 32* of knock when this happened and the thing has been screwy ever since.

I think the hesitation has something to do with the coil pack. Is the ESP Coil Pack worth getting?

Thanks for the help!

 

[WIKEDV6]

Yes it is possible that coil pack/module is bad, is there anybody local that can help you out so you can swap them out and try to solve the problem without buying it. Is there a lot of oil build up in the intake, how did the plugs look? how clean are the injectors? what kind of gas do you run?

 

[Fat Kid]

Unfortunately, there isn't anyone locally that can help me. At least not that I know of.

The plugs looked very good when I took them out. There was very little wear at all.

I'm not sure how clean the injectors are. I typically run Mobil/Exxon 93 gas.

Also, the problem with the WG hose is not the wastegate end. It's the end that attaches to the Turbo that keeps falling off.

 

[striker_29]

Hmm, could be the cam sensor maybe??? When they have a problem, they can cause all kinds of stalling, stumbling problems etc, and can also cause a mystery knock problem at low boost such as the one you describe. You might want to start the car, then unplug the cam sensor, and drive it around the block see if its drives better. Just a thought, good luck...

 

[WIKEDV6]

It doesn't matter where the hose comes off it will create an over boosting problem. What is your fuel presure? How many miles on the car? Do you know if the timing chain has been replaced?

 

[WIKEDV6]

Also try posting an inquiry in the Turbo lounge to see if there is anybody from your town ,give it a shot.

 

[Fat Kid]

I'll try unplugging the cam sensor and seeing if that does anything.

The fuel pressure is stock, 43# or whatever the 233 is set to.

The timing chain was replaced less than 20k miles ago. The car has 78k on it.

Also, when the car starts up, the IAC is very high, over 100 in drive at idle. After the car warms up, it settles down, around mid 40s at idle.

 

[Fat Kid]

Any more ideas?

 

[scottyb]

Do a thorough check for vacuum leak. Double check your IC hoses too.

 

[WIKEDV6]

Is the intake torque down properly, maybe the intake gasket. sometimes the car runs like crap if the crank sensor is on its way out. You need to check everything one by one and eliminate the possibilities. Coil first.

 

[Fat Kid]

Do you think it's worth just taking it to a damn dealer and seeing what they say? I think it might end up being a less costly process that way.