Help Anyone ! Trouble Code 51

[excobraguy]

Hi All,

I recently purchased an 87 GN with a Grooms stage 3 engine. It has a PT61 turbo with a MAF translator and extender chip, with 60 lb injectors running 18 lbs of boost. This afternoon I was driving it and it made an unusual hesitation and then started running fine. The hesitation came under a full throttle condition. I drove the car home and it seemed fine. About 2 hours later I went out to drive the car and it would barely start and run and the Service Engine Soon light came on. I jumped the A&B wires and it is saying I have a trouble code 51 (Prom error). Any ideas on where to get started to fix this? Is the ECM fried or maybe just the chip? The car also has a 140 amp alternator which has blown a few fuses already under hard acceleration. Could it have been the cuplrit here? Anyway, I love the car and I am looking forward to getting this thing fixed pronto! ANy help or comments on where to start will be appreciated. Oh, I did search and I did print off the trouble code list, so I know that much at least.

Thanks, Dean

 

[Quick6'n'-K.C.]

Did the ses light flash really fast?

Try pulling the chip out and varifying that the prongs on the chip are straight and not bent, then check the ecm to see if one of the sockets might be loose.

Reseat the chip and start the car to see how it runs, shut the car off and tryo this
If its a t-top car check the pins on the computer where the 2 bulkheads of wiring meet the ecm, pull those bulkheads off and look at the wire sockets.

Make sure there is no corrosion and the sockets are straight and not bent.

My bet is that once you do this, the car will run fine afterwards
BW

 

[jamier]

another thing

the other thing to check is the chipin the translator mine was bad a month ago and i had to have it swaped for a new 1 its rare they go bad but it does happen

 

[excobraguy]

Did the ses light flash really fast?

Try pulling the chip out and varifying that the prongs on the chip are straight and not bent, then check the ecm to see if one of the sockets might be loose.

Reseat the chip and start the car to see how it runs, shut the car off and tryo this
If its a t-top car check the pins on the computer where the 2 bulkheads of wiring meet the ecm, pull those bulkheads off and look at the wire sockets.

Make sure there is no corrosion and the sockets are straight and not bent.

My bet is that once you do this, the car will run fine afterwards
BW

I tried this but still have the same issue. I'm thinking my chip is fried. Has anyone had their chips fried before and if so, did you get the code 51????

 

[83ttypecooled]

Hi,
Code 51 is an unusual one. As a matter fact, I don't think I have ever seen it displayed. I think the most likely possibility is that, as you suspect,prom failure has occured.If you have a backup, try that. If that doesn't fix it,I would have to say the ecm has issues. I can't see any outside problems causing this. Definitely an internal affair. Good luck, keep us posted.

 

[excobraguy]

Hi,
Code 51 is an unusual one. As a matter fact, I don't think I have ever seen it displayed. I think the most likely possibility is that, as you suspect,prom failure has occured.If you have a backup, try that. If that doesn't fix it,I would have to say the ecm has issues. I can't see any outside problems causing this. Definitely an internal affair. Good luck, keep us posted.

Yeah, I'm not finding a lot of internet hits on this trouble code. I don't have the original chip to put back in to see if it would run or not. I have a call in to the guy that does Turbotweak chips. he is supposed to call me tonight. I hate to plunk down $85 for a new chip if the old one is still good. It is an extender chip. I'm wondering if anyone has ever had an altenator surge that could have burnt up the chip. Under hard throttle the headlights would get twice the brightness that they were. I am thinking I may have a voltage regulator issue on the new 140 amp altenator in the car. Any ideas anyone??? Thanks to those that have replied so far.

 

[83ttypecooled]

Hi,
I guess charging system voltage irregularities could be a factor in your trouble. But I have seen a lot of wierd stuff in my 35 years in the repair business, including reverse polarity, and charging a dead battery backwards, but through all of that,never did a prom fail. This is a very unusual circumstance.. By the way, when the key was turned on with the negatively charged battery, it blew most every module in the car EXCEPT the ecm. The prom retained it's memory. I think we are talking about an 86 Pontiac Grandam,as I recall, so definitely a GM product.
There are always new things to learn in auto repair, so I welcome elaboration regarding your findings. Good luck!

 

[excobraguy]

Come on guys in 20+ years of these cars am I the only one to ever get a code 51?????? It sucks if I am but I hope someone has some info to pass on to me.........thanks again.

 

[BlackBandit]

Do you have a volt booster by chance? If you don't have a voltbooster and you've been blowing fuses (I assume at higher rpm's) then I would assume a faulty regulator. What is the voltage coming off the back of the alternater at higher rpm's? Check it with a multimeter. FWIW If you did fry a prom and you buy a chip from TT you won't regret it. james

 

[excobraguy]

Do you have a volt booster by chance? If you don't have a voltbooster and you've been blowing fuses (I assume at higher rpm's) then I would assume a faulty regulator. What is the voltage coming off the back of the alternater at higher rpm's? Check it with a multimeter. FWIW If you did fry a prom and you buy a chip from TT you won't regret it. james

The problem just happened late yesterday afternoon and I haven't had a chance to run any other tests other than the SES test to get the code 51. Right now the car starts but will barely run. You push down on the gas and it dies. It is pouring so much fuel into the thing right now it burns your eyes standing at the rear of the car from the exhaust being so rich. Hopefull the turbotweak guy can give me some more information. I'll make sure I provide an update in case someone else needs this knowledge for a future problem. Thanks everyone.

 

[johnnyttype]

ive had a 51!

i ran into this problem after i put a new chip in my car. SES flashing, car would run horribly and die. what happened for me was that i pressed to hard on the ECM apparently and broke a connection in the board of the computer. what i did was i pulled the prom cover off the ECM and then the car ran perfect. then i tapped the chip or put a slight amount of pressure on it and the car would run very bad. i got a reman ECM and had someone more experienced show me how to install the chip. got another code 51 but this was from him bending a pin when installing the chip. bent pin back and car ran perfect! hope this helps you!

 

[TurboDave]

The problem just happened late yesterday afternoon and I haven't had a chance to run any other tests other than the SES test to get the code 51. Right now the car starts but will barely run. You push down on the gas and it dies. It is pouring so much fuel into the thing right now it burns your eyes standing at the rear of the car from the exhaust being so rich. Hopefull the turbotweak guy can give me some more information. I'll make sure I provide an update in case someone else needs this knowledge for a future problem. Thanks everyone.

Have you even tried what was suggested early in this thread?? Unplug the chip and re-seat it.
Code 51 is usually associated with slight corrosion on the chip legs, and can be cleared up by just re-seating it.

DO NOT TRY THIS PROCEDURE WITH THE KEY ON!!!

As a matter of fact do it with the ecm power wire (orange wire near the battery) unplugged to reset the ECM, to see if the code returns.

 

[excobraguy]

Have you even tried what was suggested early in this thread?? Unplug the chip and re-seat it.
Code 51 is usually associated with slight corrosion on the chip legs, and can be cleared up by just re-seating it.

DO NOT TRY THIS PROCEDURE WITH THE KEY ON!!!

As a matter of fact do it with the ecm power wire (orange wire near the battery) unplugged to reset the ECM, to see if the code returns.

Hey no offense but you didn't read all of the earlier posts:
Quote:
Originally Posted by Quick6'n'-K.C.
Did the ses light flash really fast?

Try pulling the chip out and varifying that the prongs on the chip are straight and not bent, then check the ecm to see if one of the sockets might be loose.

Reseat the chip and start the car to see how it runs, shut the car off and tryo this
If its a t-top car check the pins on the computer where the 2 bulkheads of wiring meet the ecm, pull those bulkheads off and look at the wire sockets.

Make sure there is no corrosion and the sockets are straight and not bent.

My bet is that once you do this, the car will run fine afterwards
BW

I tried this but still have the same issue. I'm thinking my chip is fried. Has anyone had their chips fried before and if so, did you get the code 51????

Anyway, the problem has been resolved....adding a new post after this one.

 

[excobraguy]

All, I tried the following and it worked, as recommended to me by Eric at turbotweak:

1 Pencil eraser
1 chip
1 needle
Using the eraser, remove film built up on chip pins. Blow off excess
Using needle, bend pins out just enough that they will make better contact.
Plug in chip and reconnect wires.

It fired right up and ran fine all 3 times I drove it last night.

Thanks everyone for your help and comments on my problem. Much appreciated! Thanks Eric for your help as well!

 

[Quick6'n'-K.C.]

All, I tried the following and it worked, as recommended to me by Eric at turbotweak:

1 Pencil eraser
1 chip
1 needle
Using the eraser, remove film built up on chip pins. Blow off excess
Using needle, bend pins out just enough that they will make better contact.
Plug in chip and reconnect wires.

It fired right up and ran fine all 3 times I drove it last night.

Thanks everyone for your help and comments on my problem. Much appreciated! Thanks Eric for your help as well!

:biggrin: Glad Eric helped you out, didnt know about the eraser trick... Was it attached to a #2 pencil?? :wink:

Did you try his website forums for the help?

BW

 

[Eric Stage I]

Yes it must be a #2 pencil eraser. :biggrin:

To clarify, the intent of the needle is to retension the pins inside the ECM chip socket, not the chip itself. It's extremely common these days for the socket to have lost some tension and not make good contact.

Glad it's working so far!

 

[Quick6'n'-K.C.]

Almost sounds like a first-aid kit for our turbo buick computers :biggrin:

BW