Okay, I just picked up a GTA today. 99k miles on it, really good condition. No leaks or anything. Well, it was weak to drive and the salesman said it was sitting for awhile so I'm betting most of the performance issues are related to that. So here's what I've done in the last 10 hours of owning this bad boy.

1) Checked spark plugs. Looked fine, but were gapped at a horrible .024, stock is .035 so I put them back in.

2) Put in a bottle of fuel injector cleaner, I know it doesn't do much. And a bottle of prestone gas tank evaporator to help remove the water. And filled up the tank.

3) New spark plug wires.

4) New air filter and the box inlet was flush against the frame, so I rotated it to where it would get more air.

5) Changed the oil.

Well, performance is a tad better, but I'm betting there is still water in the tank as it kept dying on me in the neighborhood. Finally it kept alive and I was able to drive to the store and back without a problem.

Also, the downshifting is lacking and the shift points seem to be at 4k. I remember my last TPI car shifting at 5k or so. Am I wrong?

Would crappy gas cause these symptoms?

Thanks guys!!!

 

i dont know about the transmission but im pretty sure that the stock timing was at 6*. sorry i cant help u out further than that

 

Test your fuel pressure.

Weak coil can do it but on the unlikely side of things.

Bad injectors will overheat the driver in the ecm shutting it down.

Clogged cats will do stupid things randomly as well

 

My GTA shifts right at 5500 under full throttle. My guess is that your throttle valve detent (kick-down) cable probably needs to be adjusted. I use this method: http://www.iroczone.com/techarttvadj.html

 

87TA, Yeah I remember 6* being stock, but the fluctuation is what is throwing me for a loop.

Mike_C, I thought about doing that. Do they slip over time?

3.8TA, I'll look into that too.

What about the TPS, could that be goofed?

I also checked for codes with a paperclip, the SES light never even blinked at all. So I guess I don't have codes, right?

Thanks guys.

**EDIT-UPDATE** Showed off the car to my bro and got the car to shift at 4500 this time. So we're moving on up. Another 1000rpms to go.

 

does the SES light WORK? that smy first thought, because the SES should blink code 12 for normal and nothing else if you have no codes

 

Thats what I thought. I put the paper clip in 6 and 12, and nothing happens with the key turned to acc/on. I thought it was weird.

I'm thinking the TB cables are stretched out. There is so much slack in the TB gas cable. I'm wondering if a cable stop would help things out until I get a new cable. Is this a bad idea?

 

Does the light come on with key on and not running? your not using a plastic coated paperclip are you? I have seen that done and it did not work so good!

If you are not getting any readings out of the ECM (bad ECM) it could be running in back up fuel and will run like crap.

 

Yeah, I'm getting no code readings, and yes the clip is not coated, just metal.

Here's another update, I got some TB cleaner and it helped a bit and then I pushed TB cable as far back as it could go to make up for some of the slack of the loose cable and it helped a good deal. So the shifting is now around 4700 instead of 4k, and I got some of the downshifting back. Not all of it, but its much better. So I'm looking to replacing those cables and getting the timing to 6* and it should be good to go.

Now, would a bad/blown fuse cause the computer not to be read? That happened in my Lt1 one time. I couldn't read the codes and it was because of a bad fuse.

 

I'll bet the CE light bulb is just not working. I'd pull the cluster and clean/test all the bulbs and connections. If your timing is bouncing around with the EST connector unplugged, you have another problem that needs attention.

 

The ses light works, I'm just not able to read a code. As for the timing, I just checked it. I never unplugged the tan/brown wire.

 

Are you sure you got the paper clip in the right holes ? They should be in the two upper right holes labeled a and b .

 

See, i thought it was 6 and 12, or the upper right and lower right. But you're right, thanks for posting.

Codes, 32 (EGR, due to throttle not opening all the way from the crappy TB wires), 34 MAF (from the rough idle due to the bad gas and TB wires), and 44 (lean exhaust, I'm betting from bad gas).

 

Your welcome . Glad to help .

 

You might also check to see If TV cable is adjusted corretly....it might be wrong...causing very low trans. pressure...making it seem sluggish and shift to low....

 

Yeah, I need to replace that cable. I have pushed it as far back as possible to get any sort of normal performance out of it. So I know it's shot. In the stock position, normal driving is fine, but there is no power, no down shifting and low rpm WOT shifting.

 

When I first got my IROC it was doing the same thing. Turned out my lockup converter was staying locked up.
It wouldnt hurt to replace your o2 sensor, either.

 

sounds to me like the TV....if its' shot careful cause you can burn out the tranny.

 

O2s look brand new. I'm 99.999% sure its the cable. With the cable attached to the TB wheel, it wouldn't open the TB all they way right away. With it unhooked, the TB opened all the way. I had a guy from AZTPI guy there to verify what I thought and he agreed.

Its the TV cable. If not, at least it was replaced and I can go onto the next thing.

 

I just ordered a TV cable as mine wasn't ratcheting out and self adjusting. I got mine for $32 Shipped brand new GM Cable. How much did you get yours for?

 

$55. I'm impatient. On a 1-10 scale, how much of a PITA was it to swap out? I'm about to do it right now.

 

New cable is in, not really hard to do, just time consuming. Tightening the cable to the tranny was the toughest part because it took so long. I adjusted the cable and now everthing is good.

I love the way the car performs. It seriously feels like my auto LT1 did when it was stock. Even more interesting is it feels this good at 0* timing. So I'm excited to see how it feels with 6*.

How much power is lost being at 0* timing?

 

Maybe as much as 10 hp. Used to work for pro-dyno in tempe (Many years ago) and we found on these motors, 5 degrees was about 10 hp....

 

I haven't done the cable yet. It will be in by Thursday... So it wasn't that bad to put in?

 

Glad to hear you got it man .

 

Bullydog, raised the car up, removed the cable from the TB bracket, cut the cable in half so when I pulled it out, it wouldn't snag and break something. I lowered the tranny crossmember and unbolted the exhaust hanger from the tranny, then the tranny was able to be lowered an inch or 2, enough to be able to turn the 10mm screw 1/8 turn. <----sucky part. Removed the cable. Then I fished the new cable from the back of the motor down into the tranny tunnel. The cable comes with a little clip to help insert it, there is a tiny little hook that needs to go through the eye of the end of the cable, then it can be tightened down....<------the 2nd sucky part LOL!!! And reverse.

Drknw, 10 hp eh? So could be 12 or 16hp if I go to 8*. Cool.

89-bird, thanks man. Me too.

 

I DOUBT it, because it will be knocking. 6*BTDC is the STOCK specification on the L98 though.

 

Yeah, the tough part is to get the most advance without pinging. I have stuck with stock timing for the IROC so far. Hoping my vortec 350 will be less problematic, LOL!

 

If you get pinging all you have to do is go up a grade in fuel so you can add the timeing without pinging .

 

Well I put it at 8*. All we have here in sunny AZ is good ol' 91 octane.

 

So she's all good now ?

 

I'd say so. All that's left mechanically is an alignment.

 

Good to hear that .

 

Yeah, Thats the highest we go. I dont like to mess around with mixing race gas.

 

**UPDATE: Filled up the tank, and idle is rough and no performance....AGAIN!!!! I can't even enjoy this thing yet.

I'm getting no codes, anymore. But idle is is horrible and shakey, but it doesn't die on me like it did with the bad gas. Swapped out the Left (driver) O2 as one of the old codes said lean on left bank, but no change. Checked fuel pressure and it's fine. Inspected all the wires and plugs, they were fine. I just now put in a new fuel filter, no change. I'm about to get under there and rip off the exhaust because it sounds horrible, fluffing sound, maybe it clogged within the last couple days....sounds impossible, but whats left? The engine felt really good for a day or two, so I know the motor is fine powerwise.

I used to get codes 33, 34, 43,44. But like I said above, now I'm not getting any codes. Does that point to anything?

 

I would check out the cat. Seems like when they get clogged, they really kill performance and cause running issues.

 

If the cats are bad, I guess headers are going on much sooner than planned. I hope not. I really wanted to do a 1/4 and dyno baseline this fall.

 

With all my experience with bad cats is it can cause running problems and when it is bad you can smell a rotten egg smell from the exhaust .

 

Yeah that's what I've always heard too. I really doubt its the exhaust. A couple local TPI gurus are giving me a hand this weekend to help pinpoint whats going on with this big red b@st@rd.

 

Problem is happening during closed loop. Either that, or just the shear engine temps from driving a few miles finally effects whatever sensor or wire is fouled. Any suggestions? TPI is coming over to help me out, and maybe swap out the MAF and see what that does.

 

Yea!
Well hes coming to me now!

 

I hope you guys get it figured out .

 

Another update, went over to Brians house (aka Burnout) and he helped alot with figuring out whats going on. The injectors need to be replaced #2 is shot and #3 is failing. The wires, which are brand new, are cheap and are thin and have started to crack and split open and are failing. Everything else tested out fine. MAF is good, o2s are good, FP is good, vacuum is good, ECM is good. The only thing we couldn't figure out is why the shift points are so low. 4800rpms max. Maybe when the misfiring/bad running is fixxed we can pinpoint the shifting issues.

But Brian gave me a set of 22# LT1 injectors that all ohmed out good. So hopefully I can get them flowed soon and new wires on the way.

 

I just realized we forgot to check your EGR valve with the vacuum pump but based on the misfiring we detected and bad and failing injectors I don't think that has anything to do with the problems. When you change the wires change the dist. cap and rotor also and be sure to put new orings on those injectors if you decide to use them.

Also after installing your new wires, cap and rotor use your timing light like I did on each wire to watch the pulse and make sure it is steady and even. To make sure you have cleared up the misfire issue.

wires
http://store.summitracing.com/partde...0+&appfilter=1
cap and rotor (with brass tips)
http://store.summitracing.com/partde...5+&appfilter=1

 

Im happy guys... Also, Im sorry I couldnt join in on the fun!
But, at least now.. you have a good course of action!

I tried calling GTP, left a message.. Curious on how y'all made out.

 

I had some similar issues and it turned out to be the injectors. Sounds like you are already preparing to replace them, so keep us posted...

 

Did you get the new stuff on or have you not flowed the injectors yet ?

 

No, not yet. I'm waiting for the wires to get here and I need to check on some places that check the injectors. I'll keep you guys posted.

 

Yeah please do keep us posted .

 

I think 3.8 called it way back in the beginning....