87 tbi 350 popping at idle and running rich

[devildogcummins]

Tested fuel pressure last week, key on 11psi before fuel filter and 11 at idle. changed egr valve and the popping has stopped at idle, if i give it a small rev it will pop out left exhaust still for 10-15 seconds, then idles smooth. still no codes. Have looked everywhere for a egr solenoid, but cant find one anywhere, mine is a 3 wire plug with a filter.

 

[gmbellew]

were the EGR passages clear in the intake manifold? are you sure the EGR valve is the correct type? there are positive answers negative backpressure valves. they look very similar, but they are not interchangeable.

you can test the EGR solenoid with a mityvac easy enough

 

[gpw0911]

My truck was doing the exact same thing except it was the passenger side doing it. It would idle fine and then every 10 seconds or so I would get a back fire out of one tail pipe. Check engine light was not on. I had just put on full exhaust and headers and then it started doing it. Come to find out the previous owner had the longer of the two spark plug wires going to #4 instead of #2, and when I put the wires back on after putting on the headers, I put the longer wire to #2 and started getting the backfiring. I suspected it was a spark plug wire causing it so I pulled them all off and re-did it, and that fixed my problem. Since you just did your spark plug wires, I bet you got a wire crossed.

 

[birdj81]

Hi, all my friends call me Bird. I've been a member for a few years now, but I haven't commented on anything until now. I had this same problem when I rebuilt my 305 years ago. I put everything new into the motor after having to have it bored 30 over. it had the same problems and, after looking at everything, it turned out to be a crappy, brand new $150.00 distributor. I replaced that and it has fired up perfectly every time since then. Not saying that's the same problem your having, but it is something to consider.

 

[devildogcummins]

Hi, all my friends call me Bird. I've been a member for a few years now, but I haven't commented on anything until now. I had this same problem when I rebuilt my 305 years ago. I put everything new into the motor after having to have it bored 30 over. it had the same problems and, after looking at everything, it turned out to be a crappy, brand new $150.00 distributor. I replaced that and it has fired up perfectly every time since then. Not saying that's the same problem your having, but it is something to consider.

I have thought this so many times, I cant find a factory gm or new ac delco anywhere, only reman. I might go that route if I have to. Thanks for your comment,

 

[joewhite]

My 87was doing the same thing chased the issue for a couple weeks I changed every sensor even the ecm it wound up being the ground wire for the ecm I can’t say enough how important your grounds are to these trucks good luck sir

 

[fast 99]

Didn't go back and read all the replies has anyone suggested a possible exhaust leak?

 

[devildogcummins]

Found some trash in the injectors bowls. Getting new gm injectors and gasket. Hope that might help some. Had 2 vacuum lines backwards from smog pump to tbi and egr solenoid to front of tbi. Hoping that helps too.

 

[Vbb199]

I had asked way earlier but never heard back regarding the spray pattern of the injectors, i suppose they couldve been your problem

 

[devildogcummins]

I had asked way earlier but never heard back regarding the spray pattern of the injectors, i suppose they couldve been your problem

Crazy enough spray pattern looked perfect. Might have been thin but looked ok. New injectors made truck run like a new. Have put around 150 miles on it and am loving it.

 

[Vbb199]

what a great way to close!

glad you got it fixed!

 

[devildogcummins]

Would like to thank everyone for the replies and help. Glad this forum exists, really enjoyed it the last few months

 

[YakkoWarner]

I didn't know that about the 87's. It shows live data on dad's 92 Suburban. I just assumed they were the same. Good to know

The "problem" isn't that its difficult - its that no one makes the tool new anymore and its hit or miss buying a used one as to whether or not it comes with the right adaptors and decoders. I've been trying for almost 2 years to find a tool that can give me the live data...apparently the only way to do it now is to get a special cable, a Windows 10 laptop and a person who knows how to get them to play nice with each other. Without the ability to read the live data, troubleshooting the TBI system does fall back to using a multimeter, vacuum pump and hope.

That ALDLDroid app might be easier to make work but buying the 1320 bluetooth thing doesn't seem to be possible anymore. It seems like the cable and laptop is the only option at this point.

 

[YakkoWarner]

Crazy enough spray pattern looked perfect. Might have been thin but looked ok. New injectors made truck run like a new. Have put around 150 miles on it and am loving it.

I may have to look at this myself. I keep getting lean code error and can't find it, and the spray patterns "seem" nice and even. How hard was it to swap the injectors (based on the way my wiring was butchered when I got the truck I'm assuming someone did this once before).

Someone also mentioned an intake air temp sensor - thats one I have not heard about before so never checked on it.

 

[Ricko1966]

I may have to look at this myself. I keep getting lean code error and can't find it, and the spray patterns "seem" nice and even. How hard was it to swap the injectors (based on the way my wiring was butchered when I got the truck I'm assuming someone did this once before).

Someone also mentioned an intake air temp sensor - thats one I have not heard about before so never checked on it.

I mentioned the IAT not thinking. TBI trucks don't use one TBI cars do.