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HELP 1995 5.7 chevy suburban engine runs good then starts missing

12K views 18 replies 9 participants last post by  jokerZ71  
#1 · (Edited)
I set the timing to 0 with the brown and black wire unpluged. After each replacement I disconnect the battery to reset the computer. I have replaced everything: all sensors including temp sensor, map, egr,etc. I have also replaced distributor, injectors, fuel pump, filter, computer, spark plugs, cap and rotor. The engine seems to run good but gradually over a day or so it starts running bad, surging, missing and not wanting to take off from a dead stop. It showed a code 42 once or twice but infrequently, now it shows no code. I am concerned with this problem as I am going to install a new stroker motor next weekend and if my problem is electrical I dont want to have it in the new motor. :confused:
 
#2 ·
Have you replaced the fuel filter?
Does anything look out of line on the data stream?
Are there any pending codes? (one trip codes)
I seem to recall a problem with the valves sticking open on those,(intermittently) especially when towing and the engine gets good and warm.
You might ask at the dealer if they have a TSB on that condition.They should be able to tell you. Or look online at DIY alldata
 
#3 ·
Hi,
With a code 42 it has to have something to do with the distributor system and related components. does your truck have Electronic Spark Control?

I read you replaced the distributor, how about the pick-up coil?

Have you checked the fuel pressure? you should have at least 13#P.

I would clean the TBI as well, and check the fuel spray.

I would suspect the pick-up coil as the true culprit.
Rich
 
#4 · (Edited)
Thanks for the reply. I can't tell you guys how much I appreciate the feedback!!
Yes I replaced the fuel sensor two times in the last week along with 2 fuel pumps; thinking that the first new one may have been bad. I also replaced injectors and every sensor in the vehicle. Today when driving only had minimal problems with surging etc. yesterday it was worse, but I know it will go to hell the next time or soon. The only code I ever got was 42 timing spark error. I havn't seen that code in 4 days but that's how this problem has been. I don't know what a data stream is. I replaced all plug wires,cap, rotor, distributor, and all vacuum hoses,pcv valve, everything. I even used 2 cans of carb cleaner looking for leaks. When cruising at a constant speed it will either miss or surge but not at regular intervals. I replaced both tbi injectors, and the coil. I also replaced the spark sending unit in the new distributor. I guess I can change the coil again. All of the work on this vehicle has been done over the last 9 days. I even cleaned the fuel tank just in case.I feel the problem is electrical but can't find itl
 
#5 ·
satdiver1 said:
I set the timing to 0 with the brown and black wire unpluged. It showed a code 42 once or twice but infrequently, now it shows no code. :confused:
The code 42 is the est wire you unplugged when you set the timing
I understand you dont know what a data stream is. I thought maybe you had a scanner.Sorry bout that.
In light of the issues you are having and all of the parts you replaced I am leaning toward an engine issue.
It would have been cheaper to go to the DEALER and just have the diagnose it.But I guess you know that now.
I would at least check at the chevy garage about a tsb on the truck for the valve guide issue I was talking about. The worst they can do is tell you no. If they give you some info...all is good.Best of luck :thumbup:
By the way when you said fuel sensor did you mean fuel filter?
 
#7 ·
I have a code reader but maybe I can borrow a scanner. The last time I took my other truck to the dealer for a shifting problem he charged me $1800.00 to find a wire that was shorting out on the steering collum. He had installed the wiring previously when putting in a new trans. Not going there again.
 
#8 ·
satdiver1 said:
I have a code reader but maybe I can borrow a scanner. The last time I took my other truck to the dealer for a shifting problem he charged me $1800.00 to find a wire that was shorting out on the steering collum. He had installed the wiring previously when putting in a new trans. Not going there again.
Try a different dealer. Is there a GMC place or a buick place? you live in florida , dealerships are as thick as thieves.
 
#10 ·
Yea plenty of dealers here. I will go that route if all else fails, I didn't mind buying new sensors etc. since I will be installing a new engine next weekend. I just do not want this problem to follow in the new install. All the sensors will work in the new stroker motor so its not a waste. Hell I've gotton 250,000 miles out of this motor with no problems. gotta love a sbc.
 
#14 ·
hey man, on the serious side be VERY SURE that everything is plugged in correctly and in the correct place, i say this because i was having the same exact problem with my 94 and i did everything you have done and turns out who ever had worked on it last had switch around two different plugs and it caused all sorts of problems.
hope this helps and you get things worked out soon :)
 
#15 ·
Had it at the dealer today and they said it was a faulty computer. They will have my truck ready tomorrow at a cost of $598.00. At least I get a 12 month warranty. I had just replaced the computer with one from O'Riellys. I will just take it back for a refund. I sure hope this is the only problem.
 
#19 ·
You're gonna have to do some tuning after putting the stroker in.The added displacement is gonna drive the computer nuts & will most likely cause a lean condition.You will HAVE to have a chip burned for it to run anywhere near rite.You will also need to add an adjustable fuel psi regulator & raise your fuel psi.More than likely you may need to increase injector size also.