EPROM/Display Panel Issue

[VisionOP8]

Hey guys! Ive got an interesting issue.
This past January I was excited to get a 1991 Corvette ZR-1 with 57,000 miles on it and I was thrilled to drive it. I sussed out the issue with the parking brake and finally took it out on the road. I was stunned when driving the car as it would accelerate to around 3800 RPM and then do nothing, just hesitate, then it would kick suddenly back in but the RPMs would climb slowly and theres no way I could see it reaching even 6000 RPM. In addition to that the car would die at stops and the display light for "Full Engine Power" and "ABS ON" never illuminate, not even during start-up test. The valet key would illuminate the green LED but the display would not show full engine power, and it didn't seem to make much difference either way, this thing was slow as second Christmas. I took it to Corvette of Tampa and they rebuilt one of the fuel pumps and fixed the fuel line coming from the tank and that fixed the dying at stops issue. However, the hesitant throttle remained along with the display lights issue. I went through a duffle bag that came with the ZR-1 and found an EPROM. After googling the labeling I found that it was the stock ZR-1 EPROM. I brought this to Corvette of Tampa and they installed it and the acceleration hesitation issue went away. The car is now MUCH faster and I noticed that every time I start the car, the LED by the valet key now defaults to off and I have to put the key into the Full Power position to turn it green (before it would default to green after startup).The EPROM they removed is labeled Haibek Auto Technology BFXBG2. However, I still don't have the ABS light or Full Power lights at all and they don't come on during start up test. The car does, however, have the power to kick the 13" rear tires sideways with a little throttle from a stop. I know this is a LOT to take in but I have been frustrated with this since January. The car does perform MUCH better now but I feel there may still be issues here. How can I verify that the engine is at full power or that the valet key is working properly. My brakes are a little soft even after a brake system flush so Im sure the ABS is on the fritz as well. Did the previous owner screw this awesome car to hell? Any help would be greatly appreciated. I thought I'd mention too that the people at Corvette of Tampa are amazing but they don't seem to know much about the LT-5 engine.

[secondchance]

Talk to Robbie with Corvette Masters.
http://www.corvettemasters.com/corvette_masters_contact.html

Hard to tell what was done to the car before.

[VisionOP8]

Thanks man, Im on it! I really appreciate it!

[conesare2seconds]

Marc’s chip is probably not the cause of the symptoms you were experiencing. Here’s some info on them:

http://www.zr1specialist.com/HAT%20Web/products/LT5%20Performance%20Engine%20Calibrations.htm

[VisionOP8]

I have checked out that site. The previous owner kept very meticulous service records and I still have the invoice from him ordering that chip. The guys at Corvette of Tampa seem to think something was done to the EPROM after purchase. Putting the original back in fixed a LOT of issues. Its actually fun to drive now.

[PhillipsLT5]

Send the chip back to Marc, he can reburn or check as needed, it will much better than stock in several ways

[GOLDCYLON]

Hey guys! Ive got an interesting issue.
This past January I was excited to get a 1991 Corvette ZR-1 with 57,000 miles on it and I was thrilled to drive it. I sussed out the issue with the parking brake and finally took it out on the road. I was stunned when driving the car as it would accelerate to around 3800 RPM and then do nothing, just hesitate, then it would kick suddenly back in but the RPMs would climb slowly and theres no way I could see it reaching even 6000 RPM. In addition to that the car would die at stops and the display light for "Full Engine Power" and "ABS ON" never illuminate, not even during start-up test. The valet key would illuminate the green LED but the display would not show full engine power, and it didn't seem to make much difference either way, this thing was slow as second Christmas. I took it to Corvette of Tampa and they rebuilt one of the fuel pumps and fixed the fuel line coming from the tank and that fixed the dying at stops issue. However, the hesitant throttle remained along with the display lights issue. I went through a duffle bag that came with the ZR-1 and found an EPROM. After googling the labeling I found that it was the stock ZR-1 EPROM. I brought this to Corvette of Tampa and they installed it and the acceleration hesitation issue went away. The car is now MUCH faster and I noticed that every time I start the car, the LED by the valet key now defaults to off and I have to put the key into the Full Power position to turn it green (before it would default to green after startup).The EPROM they removed is labeled Haibek Auto Technology BFXBG2. However, I still don't have the ABS light or Full Power lights at all and they don't come on during start up test. The car does, however, have the power to kick the 13" rear tires sideways with a little throttle from a stop. I know this is a LOT to take in but I have been frustrated with this since January. The car does perform MUCH better now but I feel there may still be issues here. How can I verify that the engine is at full power or that the valet key is working properly. My brakes are a little soft even after a brake system flush so Im sure the ABS is on the fritz as well. Did the previous owner screw this awesome car to hell? Any help would be greatly appreciated. I thought I'd mention too that the people at Corvette of Tampa are amazing but they don't seem to know much about the LT-5 engine.


Hello welcome to the board. The "FULL ENGINE POWER" will never come on in a 1991 ZR-1. It was a light that illuminated in the Drivers Information Center or DIC in only the 1990 models. Yes I know the script is still there but it wont illuminate due to GM changing the Valet Power key to a key module and a green LED on the lower radio surround which indicates while it is green the car is in full power mode. In 1990 a valet key was indeed just a key with an on and off position. GM Opted to not change out the DIC graphics. You may have a few issues here. I would verify that the Service Engine Light is not burnt out or has been removed. If there is a secondary vacuum leak the car will never go into full power. Do you have a scanner to find out if you have any trouble codes from the ALDL port on the lower hush panel where your right knee will normally be while driving the car? lots of possibilities faltering fuel pump ( ZR-1s have 2) bad injectors or a vacuum leak would be my best guesses. Also I am 99.9% sure Marc Haibecks PROM Is not the issue. Other than 2 guys I know personally Marc has forgot more than most could ever know about LT5s and PROMs. He is a living legend in this small community. GC

[VisionOP8]

That is some really great info thanks! Im looking into it. I had one fuel pump replaced and one rebuilt. Im not sure if the mechanic checked for vacuum leaks and I will check it or get it checked out. I wish I had a way to do that myself, but unfortunately I do not. I do know that in 2013 new ZR-1 Delphi stainless steel injectors for 90-92 were ordered from www.fuelinjectorconnection.com along with a set of new vacuum hoses and they were installed at the same time at 54,000 miles. The car is now at 58,000 miles. Thanks for the info on the "full Engine Power" light. HAHA I feel kinda foolish now and I had no idea they stopped using that light and I figured because I could still see it on the screen as a potential light that it wasn't working. haha.

[GOLDCYLON]

Im looking into it. I had one fuel pump replaced and one rebuilt. Im not sure if the mechanic checked for vacuum leaks and I will check it or get it checked out. I wish I had a way to do that myself, but unfortunately I do not. I do know that in 2013 new ZR-1 Delphi stainless steel injectors for 90-92 were ordered from www.fuelinjectorconnection.com along with a set of new vacuum hoses and they were installed at the same time at 54,000 miles. The car is now at 58,000 miles. Thanks for the info on the "full Engine Power" light. HAHA I feel kinda foolish now and I had no idea they stopped using that light and I figured because I could still see it on the screen as a potential light that it wasn't working. haha.

You are not a fool. Its a valid question. So with new injectors that potential problem area can be somewhat ruled out. What the idle on the car normally the car will high idle if a vacuum leak is the culprit or wag up and down. Did you scan for any codes ?

[VisionOP8]

You are not a fool. Its a valid question. So with new injectors that potential problem area can be somewhat ruled out. What the idle on the car normally the car will high idle if a vacuum leak is the culprit or wag up and down. Did you scan for any codes ?

Thanks man . The idle on the car is usually just below 1000rpm once its warmed up. I will research to find out how to scan for codes, I think that should really be my next step. I honestly have no idea how to do it and Ive seen things mentioning jumping connections with a paperclip. I will have to read some things again.

[GOLDCYLON]

Thanks man . The idle on the car is usually just below 1000rpm once its warmed up. I will research to find out how to scan for codes, I think that should really be my next step. I honestly have no idea how to do it and Ive seen things mentioning jumping connections with a paperclip. I will have to read some things again.

Bingo you prob have a vacuum leak 1000 rpms or just below it is way too high. Normal idle on an stock car is about 600rpm max.

[VisionOP8]

Bingo you prob have a vacuum leak 1000 rpms or just below it is way too high. Normal idle on an stock car is about 600rpm max.

Damn you're good! Okay man that sounds good to me, Im gonna get it checked out!!! You're too awesome!!!

[GOLDCYLON]

Damn you're good! Okay man that sounds good to me, Im gonna get it checked out!!! You're too awesome!!!

Well your not out of the woods yet high idle could be a idle adjustment stuck IAC etc. but now you have some areas to look at

[jss06c6]

Not sure I understand the comment that the power key is not functional in a 1991? My tune defaults to full power on start, but can certainly be changed back to valet mode with the key... ???

Sent from my XT1585 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[GOLDCYLON]

All the keys are functional unless deleted by the prom... normally to always on. The OP did not understand why the full engine power light did not come on in the DIC in his 91. That light only comes on in the MY 90 in the DIC. 91-95 ZR-1 indication of full power mode was by viewing the green led next to the valet key which indicated full power is on.