John Speake

Chris will need to fit larger injectors if he is going to dispense with the BEGI....

cfc928gt

Chris, I have Andy Keel's old boost specs for the eatons. If you measure the upper pulley diameter we can figure out what he was claiming boost should be, assuming the lower pulley is the one Andy supplied. His lower pulley was about 5" diameter.

Chris Lockhart

CFC, I'm not sure what if he kept the same diameter, but I do know that the PO had a new lower pulley machined because he kept throwing belts.

BTW, here are some pics of my set-up:

DR

Hi Chris,

Thanks for the big pics, that helps a lot...and with them big like that it is almost like being there!!

I see a few small things that pop out at me, they make not be all, or even any of your issues, but could play a role.

First, your TPS connector concerns me, it looks stressed and fatiqued. Check the integrity of the wiring at that sharp bend.

Now, I don't have much experience with that variation, but your throttle cable going over to the Throttle Body looks too tight to me. IMHO there should be a tiny bit of slack there. With it as tight as it appears (and it may just look that way) it is possible with heat expansion, flexing of the joint between the TB and the elbow, plus the natural flex of the unsupported system there, amplified by the engine "rocking" of that system at the air inlet/filter against the cross brace...you could have enough movment of the TB to cause the TPS to come off of the idle switch, especially if it is adjusted right on the edge. (this alone could cause the intermitant stalling on decel).

Again, back to the TPS, if it is adjusted right on the edge at the threshold, the tight cable and flexing could be enough to make the proper operation intermitant.

SO, if I were you, I would do the following, especailly since it si simple.

1 - Adjust the cable to the TB so there is just a tiny bit of slack.

2 - Check the operation of the TPS and adjust if needed, you should be able to hear it "click" just as you start to open the TB. BUT, putting a meter on it is best so you can see the operation of the idle switch (another advantage of a SharkTuner, you can see it operating, or not, on your laptop screen)

Try opening the TB slowly and letting it slowly as possible close, make sure you hear the click (or see it with meter) each time...then open and close the TB qucikly...then in various confirguration of speed and movement.. Basically you are trying all sorts of varying movements, pressures, speeds to try and make it fail.....IF at anytime you don't get the proper operation fo the TPS idle contact.. then adjust the TPS more liberally (opens just slighlt later as you open the TB). This will give you a little more tolorance in it's operation.

It is also possible the TPS is going bad, IIRC that verion uses the 85-86 TPS, not the 87 later version. ??

Any who, check those things as I feel they need to be addressed anyway..and we can go from there.

Oh, and don't forget to check the vacuum at idle, hot and cold, I am curious what reading you have.

Bill Ball

8-8.5 PSI? I don't think so. The upper pulley looks too large for that. And that boost would be hard to tune without a Sharktuner, and intercooling. Base was 5 PSI. Andy offered 6.5 PSI upper pulleys. Anything for higher boost would be so small the belt would slip.

That's either one of my adaptations for the throttle cable routing (over screen door wheels) or someone copied it. It should allow the throttle to be straight up and down. Here's a picture with another version of the throttle routing I made that shows the orientation. If you can turn it, you should gain cable slack, although you will need to put another 90 degree elbow in the idle control valve plumbing too, shown in the second pic to allow this rotation. Worked for me. You may need to adjust/lengthen the bracket holding the cable sheath on the top of the SC.

DR

Thanks Bill!

Chris, if you look at Bill's first pic, notice that the cable doesn't look as tensioned between those 2 small white rollers. You can just see a very, very slight "droop" there. That was what I was trying to describe earlier.

Bill Ball

Right, there should be very slight slack so the throttle seats and the TPS clicks. The cable won't jump out of the guide wheels unless the slack is way too much - never happened to me. He should be able to rotate the throttle and MAF setup so everything is better aligned with less stress on the TPS cable, as long as he adds an elbow or two to Andy's IAS plumbing. May or may not need the cable sheath bracket lengthened to get everything right. If Chris can get this to SITM, I'm sure you'll have him ripping up the pavement in no-time.

dprantl

Did you check those ISV hoses yet? I can just see them from the top pic, but not enough to see if they are an issue. Also +1 on the TPS. It is very easy to test this. With a cold engine, put your ear to the TPS and pick the throttle up listening for a *click*. Then, move the throttle all the way open, and very slowly let it back and make sure it clicks off. Do the same with after fully warming the engine up and then shutting it off.

Dan
'91 928GT S/C 475hp/460lb.ft

Harvey928

I am a first time owner and have issue since I bought mine. I have done some work replacing the idle control value, new hoses, new distributor cap, rotors. plugs, plug wiring, and various other parts. I plan on limping mine to SITM and would welcome any help in getting it running right. I would appreciate any help.

Harvey

SeanR

Nice bump.

Chris, I hope to hell you do this GT the right way. I've been dealing with your fvckups on the last one and really feel for the current owner.

Jadz928

Well done Sean! Nice positive comment. *sarcasm*

AO

Who took a giant crap in your Wheaties?

Lizard928

That is funny, a lot of us are quick to condescend POs who did hack job repairs. But the moment one of the POs is among us we cannot call them on it, or suggest not doing hack job repairs......

Then again, who is to say that he did those repairs?

But I mean, he did put that gawky hood on the car.

Jadz928

I don't have a problem, Colin... IF he knows it was him that did the work... AND he makes his own thread about his concerns.
See, here this is Chris's thread, and I'm sure he would appreciate positive comments towards fixing his problem.
If Sean is "concerned" about Chris's work, he would have been better served to help him in this thread. That didn't happen.

AO

I think Sean's basic demeanor in this thread is totally uncalled for. So what if Chirs's previous work (or someone else's work for that matter) made Sean's life a bit harder. Boo Hoo! If anything he should be kissing Chris's butt for the extra work. Did the person who bought the car not do a proper PPI?

Some people need to think before they post. Let me know when Sean decides to remove his foot from his mouth.