Follow up to Lost an need help

[Route 66]

I would like to say thanks to all of you who responded to my request for help' I think I may have found the problem. At least one of them. The low gas pressure was caused by a vacuum leak at the fuel pressure regulator. [ To Paul Workman & ZWILD1 ] you 2 got me going in the right direction. Thanks.
I am still not sure I have the 405 HP. I repaired the vacuum leak and went on a couple of test drives. I haven't driven this car much in the past 15 years or so I am not sure how it should feel at full power. It doesn't seem to have much power in the lower RPM range but pulls strong once up about 4000. There seems to be a big difference between C4 ZR1 & C6 Z06. I know the Z06 has more power and less weight but there is a Big difference. It might be because I have become accustomed to the Z06. How ever it does seem to run better than it did before I repaired the leak.
I have another question about the ZR1. A short while after buying the car new I took it in for service at the only dealer who had a factory trained mechanic for the ZR1 in my area. The mechanic doing some diagnostic checks replaced what I think was the PROM, He said the car came with the wrong one and replaced it. I still have the one he took out. It's about 3/4 inch by about 2 3/4 inches. Did any of you have that happen? Or do any of you know about a service bulletin back then that pertained to a ECM needing the PROM replaced. Is there some place I can go to read about Engine service bulletins for the C4 ZR1's. Just wondering why it needed to be replaced.
Thanks for your help.

[Top Toy]

If you have access to a chassis dyno (Dynojet et al), that would give you a direct indication of how much power your car is making across the entire RPM range. For a bone stock 405 car, you should expect somewhere around 340 to 360 RWHP @ 6000 RPM. Around 210 to 215 @ 3000 RPM.

The stock PROM should have a blue plastic cover. If you look thru one of the holes in the top of the cover, you should be able to see a four letter code, e g. BMCB (stock '93), that will tell you what version you have.

If you'd like your ZR-1 to keep up with your C6 ZO6, that problem can be easily remedied by one of the engine builders here on the forum! [emoji6]



Sent from my HTC U11 using ZR-1 Net Registry mobile app

[Route 66]

[QUOTE=Top Toy;283799]If you have access to a chassis dyno (Dynojet et al), that would give you a direct indication of how much power your car is making across the entire RPM range. For a bone stock 405 car, you should expect somewhere around 340 to 360 RWHP @ 6000 RPM. Around 210 to 215 @ 3000 RPM.

The stock PROM should have a blue plastic cover. If you look thru one of the holes in the top of the cover, you should be able to see a four letter code, e g. BMCB (stock '93), that will tell you what version you have.

If you'd like your ZR-1 to keep up with your C6 ZO6, that problem can be easily remedied by one of the engine builders here on the forum! [emoji6]



Sent from my HTC U11 using ZR-1 Net Registry mobile app[/QUOT

Thank You...
I appreciate the information on the PROM and the other. This was my first Corvette so I am keeping it as org as I can. I drive the Z06 to have fun.
I think the 405 is working. Now I can move on to my next project.

Thanks again Ellis

[Ccmano]

Find a back road or freeway on ramp and do some full throttle acceleration runs to 7000 rpm with the power key off and then back on again. There should be a noticeable difference in power particularly over ~4000 rpm.
H

[Paul Workman]

I can't imagine a mechanic swapping PROMS, unless he had access to a program and installed it into the new "chip". That swap biz, I've never heard of before. (BUT! Then again, I am not aware of anyone who's taken their Z to a dealer/mechanic either!

I favor the DYNOJET test route. We've got LOTS of graphs to compare with.

BTW.. I think you might just be spoiled. A C6 ZO6 is lighter and makes 100+ (peak) hp more and a ton more torque (mid-range) at the crank than your ZR-1. So, seat of the pants would favor the C6 (427 vs. 350!) and be no surprise there.

On the other hand, a fully ported 5.7L LT5 w/ headers, "X" pipe and a tune can make 510 crank hp at around 6800 rpm. The results on a straightaway might just surprise an LS7 C6 Z06!

[Route 66]

Originally Posted by Paul Workman

I can't imagine a mechanic swapping PROMS, unless he had access to a program and installed it into the new "chip". That swap biz, I've never heard of before. (BUT! Then again, I am not aware of anyone who's taken their Z to a dealer/mechanic either!

I favor the DYNOJET test route. We've got LOTS of graphs to compare with.

BTW.. I think you might just be spoiled. A C6 ZO6 is lighter and makes 100+ (peak) hp more and a ton more torque (mid-range) at the crank than your ZR-1. So, seat of the pants would favor the C6 (427 vs. 350!) and be no surprise there.

On the other hand, a fully ported 5.7L LT5 w/ headers, "X" pipe and a tune can make 510 crank hp at around 6800 rpm. The results on a straightaway might just surprise an LS7 C6 Z06!

Thanks
I bought the ZR1 new. When he replaced the PROM it would have been not long after I bought it. I need to look through my parts collection and find it.[ the one he removed]. At the time I never thought much about it.
What I was looking for is someone like me who bought one and took it in for warranty work at a dealer. I am not sure if he knew what he was doing. That is why I am asking my question.
I think the 405 is working now. Thanks again
Z06 performance is great.

[WARP TEN]

Originally Posted by Route 66

Thanks
I bought the ZR1 new. When he replaced the PROM it would have been not long after I bought it. I need to look through my parts collection and find it.[ the one he removed]. At the time I never thought much about it.
What I was looking for is someone like me who bought one and took it in for warranty work at a dealer. I am not sure if he knew what he was doing. That is why I am asking my question.
I think the 405 is working now. Thanks again
Z06 performance is great.

If you find the old stock prom, just send it to Marc Haibeck, tell him what your car has by way of modifications, if any, and for a modest price he will send you a chip that will improved your power by about 10 HP, turn on the cooling fans earlier and get rid of the dreaded CAGS 1-4 shift. You won't regret it. --Bob

[32valvesftw]

There are apps you can download that will use the accelerometer in your iPhone, that will give you approximate 0-60 0-100 and 1/4 times. The app I downloaded was free. Give that a try and let us know the results. Yes driver skill has a lot to do with it, but if you are putting down 14 - 15 sec quarters then you KNOW there is a problem.

[Demps]

Marc Haibeck, like with most things, has the answer to your dealer fix:

For ’93 to ‘94’s GM issued BMCB with Product Service Bulletin 576514 dated 18 September, 1995. It addresses a problem with a sag or surge on light throttle acceleration below 2500 RPM. It also corrects an intermittent ASR error that a few cars had.


Found here:
http://www.zr1specialist.com/HAT%20W...0For%20You.pdf

Ted

[Route 66]

Originally Posted by Demps

Marc Haibeck, like with most things, has the answer to your dealer fix:

For ’93 to ‘94’s GM issued BMCB with Product Service Bulletin 576514 dated 18 September, 1995. It addresses a problem with a sag or surge on light throttle acceleration below 2500 RPM. It also corrects an intermittent ASR error that a few cars had.


Found here:
http://www.zr1specialist.com/HAT%20W...0For%20You.pdf

Ted

DEMPS: Thank You.
This is what I have been hoping for. I was thinking it happened earlier in my ownership. I was wrong. You and the other Gear Heads on here have taken a weight off my back. I didn't want to take my car in for repair and leave it not knowing how it would be cared for. I like doing my own work but this one was tough without a Tech I or II. I have a good code scanner but the problem I was having would not throw a code.
I can now move on to my next project.
.
.......................Thanks again Ellis