Another "Dies at stoplights" Issue

[ColtSteel45]

Hello, I'm new to membership but have been lurking for a while. I've read countless threads and really appreciate all of the information here. So thank you for that!

I have a 1987 V10.. single cab short bed 1/2 ton 4x4 with the TBI 350. Quick back story.. My brother built this truck from stock in the early 2000s and its passed through 2 other owners before I picked it up about a month ago. Both owners abused her and didn't have much mechanical experience other than dropping it off at repair shops.

My issues.. Mainly she dies at almost all stop lights, so I can recreate it typically. It also dies at idle when it hits operation temperature the first warm up after a complete cool down. After restart, it will idle for hours with no issue. When it dies at stops, I can knock it into neutral (auto trans) and it fires right up every time. I'm not sure if its related but it will also fall on its face under load and heavy throttle like pulling a grade if I stomp the pedal. It will studder for about 4 seconds, wake up for 6 seconds, then studder again. I can also recreate that on demand. That only happens under speed (50mph or so) in the top 3/4 throttle). I can ease through the throttle and get above that speed with no issues of cutting out, only heavy throttle causes it.

My parts/tests.. New IACV, New TPS (voltage tested and no dead spots, adjusted correctly) New EGR, New MAP sensor, New plugs, wires, cap and rotor, Vacuum line routing confirmed correct and building vacuum when/where needed, Timing adjusted multiple times in different positions, New 02 sensor, New external coil, I'm sure other small stuff. Tested fuel pressure at the filter and its steady at 11 psi.

I'm getting really tired of throwing parts at it, but I dislike TBI so its really all I know what to do. I'm looking for some advice on what to do next. Injectors seem to have a nice spray pattern with no dripping. All grounds are there (plus a few extras that I've added). Before I throw out my opinion on what it seems like to me, I'd love some feedback! Thank you!

 

[ColtSteel45]

Oh! I don't have any check engine lights coming on or staying on consistently. One time I was lucky enough to grab one and it came up as "22" TPS voltage was under 0.2 volts for 2 seconds when the engine was running. Maybe that's something to chase but I've tested the TPS without the engine running multiple times, and the TPS itself is newer.

 

[gmbellew]

i recommend getting ALDLDroid and a Bluetooth ALDL cable to see what the computer sees. it's a minor investment for near-scan tool capabilities that will make diagnostics on TBI much easier.

that and the drivability and emissions manual in the reference library of this forum. It is like the TBI Bible.

with those two things, you can go far with TBI diagnosis

 

[ColtSteel45]

Wow, I just did some research on that app and it sounds pretty impressive on paper. Maybe even worth buying an android based tablet for. I use Apple, they seem to be android only.

 

[gmbellew]

Wow, I just did some research on that app and it sounds pretty impressive on paper. Maybe even worth buying an android based tablet for. I use Apple, they seem to be android only.

it's a game changer for diagnostics. TBI can still benefit from some old school mechanics (vac gauge, etc), but being able to see what the computer sees is huge to make sure all the sensors are working properly.

 

[ColtSteel45]

She's back to life and running better than ever! Figured I'd give this topic some closure. After all of the parts I threw at this truck, the last one I tried was the ECU. That was it! I got lucky and found a friend with the same year and engine combo so I gave it a shot. I even left his PROM chip in, just incase. 5 minutes to swap ECUs and she's running significantly better than ever and zero hesitations and stop light deaths. He also set me up with a nice Holly TBI unit that I'm waiting on a rebuild kit for so hopefully she'll be back to spinning her 38" tires soon enough!