DIY PROMDo It Yourself PROM chip burning help. No PROM begging. No PROMs for sale. No commercial exchange. Not a referral service.
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I am getting a code 34 in my 85 T/A, 305 TPI. I read in my other post that these proms had problems with a false 34. The only problem I am having is a very little rough. But I think is my worn out TPS. Could I be getting the false 34 and need to replace my chip?
I have a 85' with the 870'Ecm and I also have the false code 34
only happens if I let it idle to long. To find out if you need to replace chip open up the cover on your Ecm and see if the the code on the prom Ends in (HLK) If so you have options.
Either replace the prom with a updated one (HLM) or
Change to a 165' Ecm Or SD system.
You can get the updated prom form the GM Dealer Ship or if they are over $50.00 go to rockauto.com
Just my .02
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Originally posted by ss85tadude I am getting a code 34 in my 85 T/A, 305 TPI. I read in my other post that these proms had problems with a false 34. The only problem I am having is a very little rough. But I think is my worn out TPS. Could I be getting the false 34 and need to replace my chip?
According to the TSB on the false code 34, you must first verify that it is indeed a false code, in other words, follow the dignostic procedure to verify if the MAF is bad. It actually starts by saying to make sure that you minumum idle is set at 500 RPM's. If all checks out, then the updated PROM is the solution.
So, yes it could still be a bad MAF.
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Originally posted by JP84Z430HP According to the TSB on the false code 34, you must first verify that it is indeed a false code, in other words, follow the dignostic procedure to verify if the MAF is bad. It actually starts by saying to make sure that you minumum idle is set at 500 RPM's. If all checks out, then the updated PROM is the solution.
So, yes it could still be a bad MAF.
Yes I forgot to mention to test the MAF Thanks for the reminder JP84Z430HP, anyways the false code Has something to do with the fact that somany Chips in 85 Were programed with out covering the Erase Window on the chip and over time it corrupts the Programming.
Originally posted by ss85tadude Thanks guys how do I tell if the MAF is bad?
Someone told me two ways:
1. With car running tap of maf with a screw driver and if car stumbles it is bad. (was kinda weary of this one but it stumble)
2. I can't remember the Specs but test with a DVM Ask around and someone will know, Probally Grumpy would know the answer to this one. I did it like 4 months ago and didn't write it down.
Originally posted by Grumpy Normally, if it corrupted the programming, the checksum would change, and turn on the SES light.
Well in my case if I start the car a let it Idle a really long timewith out actually Driving the car The SES light comes on and the Idle will start surging, Clear codes and then I start car with out letting it Idle but a short time I can drive for hours and no SES light, nut get caught by a Long Winded light and theres the SES light.
Originally posted by MTPFI-MAF Well in my case if I start the car a let it Idle a really long timewith out actually Driving the car The SES light comes on and the Idle will start surging, Clear codes and then I start car with out letting it Idle but a short time I can drive for hours and no SES light, nut get caught by a Long Winded light and theres the SES light.
What code did it set?.
Or was it a soft fail?.
Prolonged idles will often set a 13, or lean code soft fail (ie light no code). As it first warms up you have enough richness, that the O2 wakes ups, but just at a steady idle things can do steadily lean, and then the ecm thinks the O2s died.
And if you have headers or low restriction exhuast, it can make matters even worse.
Well the code it sets is a code 34, I have tried a ecm from a friend that has the (HLM) and the problem dissapears also put his prom in my ecm and mine in his and He gets the same thing. so In my case I am pretty sure it is a buggy prom.
For price of the updated prom I can get a used 165' then according to Mike Davis site http://www.eecis.udel.edu/~davis/z28/ecm_swap/ I can do 10 Repinnings 1 removal, 1 addition and 2 splices and I can plug a 165' into my car. I want the faster ALDL anyways so this is the direction I am going.
WOO HOO! I got a new chip and it fixed my code 34. Still need to a little with my idle.
Thanks guys. With out this website I would have bought a new MAF and would have been SOL when that did not fix it. WOW! Somebody should inform the parts stores.
Originally posted by ss85tadude WOO HOO! I got a new chip and it fixed my code 34. Still need to a little with my idle.
Thanks guys. With out this website I would have bought a new MAF and would have been SOL when that did not fix it. WOW! Somebody should inform the parts stores.
Glad to see the problem is solved, Where did you order the prom and How much was it. Just wondering
Near Future Mods: 383 Stroker with Dart Heads, 234/244 CompCam, '165 ECM conversion, SLP differential
"1985 305TPI Iroc, free, modifications and repairs, about $4000, the look on the face of guys with a 350 when they find out they just got wasted by a 305, PRICELESS"
Iv got an 85 Trans Am w/ 305 TPI and swapped a 350 keeping the TPI but it wont start..it turns over, has fuel pressure
What Prom do i need or what ECM's can i swap in with no modifications that will run my 350
Ok when You Kept the TPI did you Buy Larger Injectors or are you still running the 19lbs 305 Injectors.
1985 There wasn't a 350 Tpi available only a 305Tpi For a Trans am And for a 350 with the 1985 870' Ecm Your gonna need a Prom from a Corvette.
Your options are:
Ac Delco # 16052307 4-SPD M/Trans (MH5) 2308HLS www.rockauto.com Price $43.99
Ac Delco # 1227805 4-SPD A/Trans (MD8) 3200HLH www.rockauto.com Price $50.79
Not Sure But You might also need the calPak. At the botton of this picture Link Provided By Rbob are what the prom and Calpak look like for a 870' or similar ECM
If ya need the calpak the Ac Delco # 16042430 for $18.57
If you are serious about tuning your car and want to learn I would recommend looking in to the Swap form the 870' to a 165'
Originally posted by ajm_shorty Yes i put 24lb. injectors in
well for now i just want to get this thing runnin so im not planning on going to the newer computer until later
So for now which one of those proms do i need and also what is the part number for the calpak
I have an 85 t/a TPI 700r4 auto trans
No calpac in the 870 ECM, that part is actually built into the computer.
If your 350 won't start on the stock prom you may have other issues. I ran my 350 on the stock 870 & 305 prom for break in of the cam and for the first 500 miles. It would start cold just fine and needed "help" to start when warm.
You need to hit the basics, are the injectors firing? Is there a nice hot spark? If it won't start you are missing one of those two.
