1989 C1500, EGR, Headers Question

[Erik the Awful]

There's a hundred ways to do it right, and just a handful of ways to screw it up.

I think you got that back asswards man!

Nope. It's not rocket science, but some people try to make it out to be.

 

[FullBlowncustoms]

It's fixed... Was all my fault. When I put on all the new parts she ran awesome for like two hours is all. Then it got that flutter sound out the pipes in rear. Hotter it got the worse it got with sporadic misses. I fired it up this morning in the dark at 5:00 am... Seen no crossfire. I pulled the plug wires off to loom them nicer. AND THERE IT WAS !!!!! I used that Die E grease on the plug boots. Inside it was covered on the terminals, and the spark plugs also. I can only assume that as it got hotter next to headers after 2 hours it ran all over inside the boots. It was like globs and BB dots inside. And I only used a bit around the edge of boots with a Qtip.. but inside looked like packed with Vaseline. Sprayed the boots all out, and the plugs. Fired it up and instantly knew it was all set, no more slight miss on and off. Stupid me... ECM still gets no signal, but FK it she runs bad *** again .... Learned a lot from everyone's help... THANK YOU VERY MUCH !!!

 

[FullBlowncustoms]

Oh and ALSO the timing light now works when motor is hot. Before the light would only work over night sitting with cold start... That stuff is the worst thing that could have happened to getting a good clean contact.. It basically insulated it from getting clean contact LOL... I only used it because the wires were expensive...

 

[GrimsterGMC]

Oh and ALSO the timing light now works when motor is hot. Before the light would only work over night sitting with cold start... That stuff is the worst thing that could have happened to getting a good clean contact.. It basically insulated it from getting clean contact LOL... I only used it because the wires were expensive...

Quite often it is something that we have done, so we don't even consider it a possibility, that turns out to be the culprit. Intermittent electrical problems are the hardest to trace as it has to be faulting to find it and it never does at a convenient time to trace. Glad you fixed it, I know how frustrating it can get.

 

[FullBlowncustoms]

Quite often it is something that we have done, so we don't even consider it a possibility, that turns out to be the culprit. Intermittent electrical problems are the hardest to trace as it has to be faulting to find it and it never does at a convenient time to trace. Glad you fixed it, I know how frustrating it can get.

Oh yeah!!! Hot Rod guy's never can sleep at night thinking LOL... Drive ya crazy. And was all a bad mistake by me...
Now that she runs clean with no on off sporadic misses..... Leads me to the ECM, Inside is two chip things, Prom? Cal Pak? Chip? IDK.... Where do I buy those two? The ECM is 1227747 Serv NO#

 

[GrimsterGMC]

Oh yeah!!! Hot Rod guy's never can sleep at night thinking LOL... Drive ya crazy. And was all a bad mistake by me...
Now that she runs clean with no on off sporadic misses..... Leads me to the ECM, Inside is two chip things, Prom? Cal Pak? Chip? IDK.... Where do I buy those two? The ECM is 1227747 Serv NO#

There are 2 methods that I know of to modify the tune in our early GMT400s. One is to change the socket on the board to accept the newer style chip that you have to take out to flash with a new tune and put back in again which is quite difficult where our ECM are placed. While I am not actively promoting for this company, I am using DynamicEFI.com who replace the whole circuit board with an onboard flash memory so you only have to plug a data cable into it and can do your tuning on the go. It also offers a range of other benefits that you can see on their website. There are others on this forum that have been using EBL longer than me that can offer more advise if you ask them.

 

[FullBlowncustoms]

There are 2 methods that I know of to modify the tune in our early GMT400s. One is to change the socket on the board to accept the newer style chip that you have to take out to flash with a new tune and put back in again which is quite difficult where our ECM are placed. While I am not actively promoting for this company, I am using DynamicEFI.com who replace the whole circuit board with an onboard flash memory so you only have to plug a data cable into it and can do your tuning on the go. It also offers a range of other benefits that you can see on their website. There are others on this forum that have been using EBL longer than me that can offer more advise if you ask them.

That all good for going all out, and money.... But she is just a weekend fun driver as long as roads not wet, rain etc.... BUT where or who can I get the two new STOCK Prom? Chips? to go back in this ECM? Maybe my old ones I put in the new ECM are bad, I have no idea.

 

[Scooterwrench]

Cool!!! Glad to here you got it purrin' again. I use the dielectric grease to but like you did with a little on a Q-tip. I use it as a release agent. After those boots have been on there a while they can be a bear to get off. Grimstar is right,EBL is the sh*t. Not to awful expensive for what you get and Dynamic will send it plug and play for the most part. You have to enter the basic parameters then it will self learn or you can carry your laptop and make changes on the fly. If you just want to get started you can buy the 27SC32 chips,download a tuner program and buy a chip burner and burn your own tunes. The 27SC32 can be erased with UV light and reflashed but erasing is a slow process. If you go that way buy a dozen at a time,they're cheap. The next option is the 16197427 ECM conversion. The 7427 uses the 27SF512 chip that is electrically erased and runs at a faster processing speed so faster air/fuel mix and timing events(and we like faster).
I'm in the process of doing the 7427 swap on ol Smoky now with a remote chip holder mounted in the glovebox so I don't have to pull out the ECM every time I want to burn a new tune.

 

[FullBlowncustoms]

Cool!!! Glad to here you got it purrin' again. I use the dielectric grease to but like you did with a little on a Q-tip. I use it as a release agent. After those boots have been on there a while they can be a bear to get off. Grimstar is right,EBL is the sh*t. Not to awful expensive for what you get and Dynamic will send it plug and play for the most part. You have to enter the basic parameters then it will self learn or you can carry your laptop and make changes on the fly. If you just want to get started you can buy the 27SC32 chips,download a tuner program and buy a chip burner and burn your own tunes. The 27SC32 can be erased with UV light and reflashed but erasing is a slow process. If you go that way buy a dozen at a time,they're cheap. The next option is the 16197427 ECM conversion. The 7427 uses the 27SF512 chip that is electrically erased and runs at a faster processing speed so faster air/fuel mix and timing events(and we like faster).
I'm in the process of doing the 7427 swap on ol Smoky now with a remote chip holder mounted in the glovebox so I don't have to pull out the ECM every time I want to burn a new tune.

that is very cool, NICE !!!

 

[FullBlowncustoms]

I'm trying to track down why the ECM still gets no signal at A-B terminals. I pull the cover off the firewall, There is a White wire just dangling.... Anyone have a 88-89 that has that wire? Makes me wonder now, because one of you guy's posted a pic of the A-B terminals what they do. Think A said Distrib ground? B is ECM Diag? That wire reaches the distributor. But no place to mount it unless they did something funky with a nut on the underside base of distributor with one of the Cap screws? When I got the truck the one cap screw was rotted out, had just one screw holding the cap on...

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