Just to close this thread out, after going through the code 42 troubleshooting steps, I put the original ECM back on and mailed the reman'd one back to ACDelco. No more code 42 after that. Engine is...
Type: Posts; User: GetItBilly
Just to close this thread out, after going through the code 42 troubleshooting steps, I put the original ECM back on and mailed the reman'd one back to ACDelco. No more code 42 after that. Engine is...
So I haven't really started troubleshooting the code 42, but now I'm wondering if I should go straight to swapping the "new" reaman'd ECM out for the original. I ask because most recently, while the...
Thanks for the help! I knew I'd probably have a few more things to work out after this, though. Now the truck throws code 42 for the EST wiring after idling for 4-5 mins. I'll have to go through that...
It had the wrong injectors! Got new 61 lb injectors installed and the top end of the TBI rebuilt. I could immediately see a huge difference in the size of the spray pattern coming out of the new...
I don't want to jinx myself, but let's say the injectors don't help, so then I take the valve cover off, measure rocker lift and find out I have an aftermarket cam? Do I have any options other than...
Yup, the TBI (17087020) is appropriate for an 87 Truck. (http://www.carburetion.com/CarbNumber.asp?Number=17087020). I read around a bunch and 61 lb injectors should be the right ones for 5.7 truck,...
Maybe the blue color on the injectors isn't as meaningful if they are aftermarket, but the only OE injectors I can find that would have had blue on them were either for a 4.3L or a big block. Looks...
I didn't know what a prom broadcast code was until after I installed the ECM, but I did write down what is apparently the Prom ID (3542) and, according to this site, it's correct for the truck:
...
Thanks, guys.
myburb - yes, both injectors are spraying. I've taken the timing light to them and don't see any big drops, either.
donf - Thanks, I will check out the manual. I already have the...
The only way I can get a steady rpm is by either unplugging the electric connector from the map sensor or removing the vacuum hose from the map sensor - both of which, I assume, force the ECM into...
Other thing to add is that when the rpms start dropping and cycling back up when I hold the throttle at higher rpms, live data seems to show that IAC isn't moving, so I guess it's the timing getting...
New ECM did not change behavior, it was worth a shot for $15.
With tan/black wire disconnected, max engine vac was achieved around 10-12 degrees advanced. But, per info on the truck's shroud,...
Sorry, either I'm totally missing something or I didn't explain what's happening in the video clearly. What I intended was to ask if I can focus on investigating a (hopefully) short list of specific...
Cats are long gone on this truck. I'll try the TPS idea next when I have time.
I guess one thing I could use some opinions on is what that video I posted proves. Could a vacuum leak still be a...
https://www.youtube.com/watch?v=33L2AwntWlE
Thanks for the feedback, 1project2many.
I think my map sensor is providing the proper readings. Video above shows map sensor voltage, vacuum tee'd...
Yeah, sorry, I meant the problem I want to solve is why does vacuum / timing advance momentarily but repeatedly drop when I raise rpms above idle and hold it there (while in Park)? My truck does have...
First, thanks in advance for all the helpful information on this forum. I've got an '87 GMC V2500 w/ HD option. It stumbles and bumbles under load. I've googled the hell out of my issues and below is...