I had the same problem with my car falling on it's face after 3000 rpm. It was so slow it was crazy. I had a new 350 gm crate engine, new fuel injectors and prom chip and a new computer, also had new fuel pump. First I checked for fuel leaks cause I knew I wasn't getting enough fuel pressure. Then I put in new fuel pressure regulators, still nothing seemed to work. Then one day I decided to change the fuel filter, and man did that solve every problem I had. The car had amazing power and pulled hard all the way to 5000 rpm. Try changing the fuel filter, just my 2 cents. Oh, one other thing that made a difference in the idle and power of the car was putting on a new 02 sensor when I did the fuel filter. Hope this helps. Good luck.

 

The O2 sensor has been changed just @ 2weeks ago. I have not looked at the fuel filter though. I'll check it out. Thanks.

 

Well I have some new issues. I think the ECM is on the way out. The car hiccups for a second while driving. Actually dies and restarts. SES light comes on and lights go out for a second. Then everyting comes back on and is fine.

Might swap out the ECM just to be sure.

 

That doesn't sound indicative of a faulty ecm. Sounds like a faulty sensor or wiring. If it's setting a code then pull it and see what it is . I swear your car is only acting up when I'm not around...
How's the warm idle doing? In either case, get some winaldl datalogs of the problem to shed some light on this NEW problem.... don't you love old cars, lol

 

I didn't take it to the track because it was acting up. So I still don't have any times with the new fuel pump yet.

If my laptop has some juice left in it. I'll take it for a spin tonight.

 

By the way Jon, I burned a new chip for it but just had not put it in. Since it was acting up I put the new chip in. Just incase there was something up with the chip or the bin. But I have not taken it out for a spin yet.

 

Could also be a flakey eprom or a bad contact at the ziff causing the computer to intermittently lock up. The hiccup could just be the ecm restarting.

 

i posted this a while back but dont think i had a response. i had computer tech solder in a standard socket then afteer realizing the bene's of a ZIF i inserted(not soldered) one. day one i had a loose connection and CE light comes on and limp begins. lucky me on a quiet street so reinserted ZIF and prom and all was good. seems once a month the prom loosens in the ZIF or i get a poor connection and need to reinsert prom only. this occurs more now due to cam shakes car a bit at low idle.

 

Not hi-jacking but merely pointing out. The clamoring for more TBI tuning info could be this post lots of good info in it, just need some serious pruning and/or cutting and pasting.

later
Jeremy

 

I've got a tech article that's just about finished that goes through the details on TBI tuning with factory code. I just haven't finished it yet... time limited. The article or website as it's becoming, is very newbie friendly with lots of comparison charts and explination captions. I've disected the various GM TBI bins and comparted them to each other. The 2 major comparisons are between Auto and manual on the same motor and cali vs fed emissions which is REALLY interesting to look at. There's just so much different between the auto/man bins that it's taking me longer to complete.
Also... if the superAUJP is the best you TPI guys can come up with for a starting bin then some people need to try again. That bin is horrific in everything I've tried and it starts with the main SA table being so fubar. I'd like to eventually develop a wizard program that asks questions and spits out a good starting bin. It now only takes me about a half hour to sit down with a guy and come up with a bin that runs great where as it used to take me hours even a hole evening!

 

lol

No comment on the Super AUJP bin, I dont use it and dont want to. I go to work using virgin ANJF or AUJP depending on mood and computer.

Kind of off topic now though :-)

But defintiely let me know when your stuff is finished and resentable, would love to link it thru the ongoing tuning bible.

When am I going to see u aorund next?

later
Jeremy

 

Next pow-wow which is coming up.

 

Azvol, Did you ever find the problem?

Some things Id think of are the cat and maybe an ignition fault. Also, the 1+ volt O2 readings indicate very rich. My O2 shows about .930 volts at 11-11.5:1 or so on the WB. Just taking fuel out could really help. Also, maybe try putting a vacuum gauge and testing for an exhaust restriction. When you snap the thottle closed after revving the motor up to around 4000 the vacuum should snap up to 25+ inHg.

 

I think the problem was somehow related to the electronic correction device for the speedometer. I took it back to the shop that put it on and they rewired it. Has not acted up in a few weeks. Seems to be ok now.

 

Did you do this to correct for a gear change? I'm planning a 3:73 rear soon and wondered should I hunt the correct trans speedo gears or what. I wish that you could correct for the change in the chip.

DM

 

Hey DM, I swapped to 3.42 gears and bought a Dakota Digital SGI-5 to try to correct for the gears. I haven't installed it yet, but I'll let you know how that works.

Jim

 

Kool.......how much do those cost?

 

I think I picked mine up for about 50 bucks. I believe they go for 70-80 new from Dakota Digital though. Every so often one turns up in the classifieds on here. It's kind of a PITA to swap the gears in our 5 speeds.

 

Bron, couldn't you just use a 7 tooth drive gear with a 19 tooth driven gear for 3.42 rear?

OTOH, if someone wants to install 3.73s...youre SOL because they dont make the 21-tooth VSS gears any more

 

Well, yeah I could get the speedo gears. But I saw this thing for pretty cheap and I didn't feel like tearing down my trans to install those gears.

 

The one I got was like $250.

Just make sure you splice it in after the speed buffer. That was the problem I had. If you splice it in before the speed buffer then the ECM gets two speedo input data streams. That's what they told me anyway. Seems ok now. And the cruise control is a lot smoother.

 

hey azvolfan when you got your car dynoed about that mustang, was it a corbra and was it also white? by buddy has one a got it dynoed a while. he has a whipple supercharger its also thier for tuneing he was pushing about 500 hp to the wheels and just instaled nitrous with about 660 something horse power.
just wanted to know if it was him.

 

It could have been him. I thought the car was gray. But it could have been white. I did not see it in direct sun light. It was probably his. I'm guessing not too many 600hp Mustangs around.

 

I should have some good solid time for my car in about a week. The Phoenix thirdgen gang is doing a BBQ and trip to the track on the 11th.

 

Well we had our BBQ and it was good to meet the Phoenix gang. After the BBQ we all went to the track. Some did well some did not. I however did not.

First run was an uneventful 16.4. Next run was a 16.1. So I'm running slower after the new injectors and new fuel pump.

I'm close to giving up!!!!

 

DONT DO IT BILL!!!

 

Must have been because of that damn tech guy who took all your beer.

Seriously though, I'm sure there is an answer somewhere as to why the car isn't responding. We are having the same issues with the 95Z28. It will come around...

 

Have you checked your WOT AFRs with a WB O2? Is your cat plugged up?

 

I had the cat checked and it was totally clean.

Prevost is bringing out a WB when he gets here in two weeks.

So we'll check it out then.

 

Hi, a clogged CAT should show up as a rising MAP value. If the exhaust can't get out the intake air can't get in. Then the MAP increases.

May not be a bad idea to check the cam timing. . .

Al.

 

Having done no WOT tuning other than "look" for knock... well you're still on the slow side . Something's gotta compare. It's really easy to swap in the dyno tune chip. When we go to the track we'll run that chip as the base although we know for a fact that it's running a over 40 degrees and knocking like crazy. It's up to you.
We got the part throttle down as near perfect as you can get with a cat. Mileage has increased, no more knocking, etc. I'd say we've got one last job to do and that's to get the wideband on. If there is a remote area to tune we can get performance data from looking at the time and vehicle speed. At 17 times a second the resolution is enough to make significant gains.
I still can't believe you didn't gain anything in the 1/4. What where your other runs when you ran the 15._ with the dyno tune? Could that have been a fluke if the rest were in the 16's? Are you going to let me drive it ?
This isn't of great concern but if you've got the weather report on the time slip I'd like to see that as well.

 

The other runs when James did the 15.5 was two 15.6 runs when I was driving. As far as the weather last night it was low humidity and probably about 90 degrees. Track elevation is probably about 2500 ft.

As far as driving the car, ofcourse you can. I should have let you last time. didn't think about it.

Would it be easier to tune a chip for daily driving and one for the track than have one chip try to do it all. I have not problem swapping out chips if that is what needs to happen.

 

What fuel pump did you replace your old one with?

Hang in there man. If there is one guy that will get you going JP is the man.

 

AZ you "should" only have to run one chip that gives max performance and drivability.

JP what wide band unit are you using?

 

Using a derivative of the DIY-WB but one that is smaller, more efficient, and can use 2 different NTK sensors.
1 chip is all you need, unless you're having troubles passing the sniffer during inspection.
Let's start with some simple stuff... how's that air cleaner look? Are you getting WOT with the floor mat? Do a WOT blast in 2nd gear and turn off the ignition (with your foot still WOT) and through it into neutral, coast over to the side of the road. Now check a spark plug. It'll tell you if you're too rich or too lean.

 

I'm pretty sure it was a stock TBI fuel pump. The mechanic I go to would not put in anything else unless I tell him different and I didn't.

 

What would I be looking for with the spark plug?

 

Are you sure it is supplying enough fuel at WOT under full load? When JP gets that WB hooked up he will be able to track down your problem. Keep the faith.

 

Ok. I'm hanging on!!