95 2.3L Rough Idle

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sevlor
Regular Member
Posts: 6
Joined: Tue May 08, 2018 10:10 pm
Location: Illinois
Isuzu vehicle(s): 1995 Isuzu Pickup Regular Cab

95 2.3L Rough Idle

Postby sevlor » Thu May 17, 2018 12:58 pm

Hello, I am very new here, have only owned my P'UP for a couple weeks now, been trying to diagnose a problem I have been having, hoping someone can shed some light on what it could possibly be.

A little back story, I bought this truck a little over 2 weeks ago, drove it about 70 miles back home, made it there with no problem with only the instrument cluster zip tied to the support bar in the cab, no diag lights hooked up as the entire dash has been removed by the previous owner in order to paint it, he had ran out of time to put everything back together. I noticed while driving home going through the bluffs outside St. Louis that it had no power climbing out of the hills, I figured it probably could use some love I'll deal with it after I get it all assembled. I spent a few hours that night and get everything put back together with no guide (this truck is surprisingly easy to work on interior wise), started it back up and found it had a check engine light. I figured I would wait until I got my chilton's in along with my filters from rock auto. A buddy of mine helped me with looking at the truck as he noticed it idled a little rough which I had noticed too. Another issue it had was with if you blipped the throttle it would hesitate, he attributed it to possibly a bad EGR. While looking at things we found a vacuum leak at the TVV, the previous owner had replaced this with a brand new one, but used Fuel line to hook it up, and I believe when he was hooking the lower barb up to the intake manifold he partially snapped it. I ended up repairing this and hooking it all back up with proper vacuum line, had no effect. I finally got my chilton's manual in and found out how to get the codes from the computer, it spit out a code 34, which from what I read in the book said EGR temp sensor fail, so this seemed to confirm my buddy's suspicion that the EGR was at fault. I bought a hand vacuum pump the other day and hooked up the EGR and it holds vacuum and moves freely, this lead me to google only "Isuzu code 34" to which I found with the 2.3L TBI this was a code for a failing MAP sensor. I then went and tested it with the vacuum pump and it passed, but me and my buddy started looking closer at the vacuum system and found that the MAP and the EVAP had been flipped, we flipped these back to where they were supposed to go and my check engine light went away.

I cleared my codes and I currently have no check engine light, and no codes in the computer, how ever I still have a rough idle, can't seem to find any vacuum leaks. I can drive the truck light this, but if I come from a higher RPM and press the clutch to come to a stop, it will almost die, in fact this morning It did die on me and I had to pop the clutch to start it back up coming up to a stop sign. I did notice that this morning form a completely cold start, this truck idled fine until it got up to running temp and it went back to a rough idle, I am running out of ideas on what to check for this now, me and my buddy plan to check the ignition timing tonight and see about advancing or retarding it a little, but I am not entirely sure if that will work or not. It does seem to be running a bit rich if that helps with helping me diagnose this thing.

sevlor
Regular Member
Posts: 6
Joined: Tue May 08, 2018 10:10 pm
Location: Illinois
Isuzu vehicle(s): 1995 Isuzu Pickup Regular Cab

Re: 95 2.3L Rough Idle

Postby sevlor » Thu May 17, 2018 10:37 pm

So new problem, on my way out after work tonight the truck lost power and I was unable to accelerate, I turned off onto a side road and it died. I tried to start it back up and it was idling much rougher than before and as soon as I hit the gas it died. I pushed it into a parking lot and let it sit for a bit, figured maybe the fuel gauge wasn't working right and I may be out of fuel. Had a friend bring me a some gas and it still failed to start. I hooked up the diagnostic wires and it gave me a code 45 (Fuel metering) which from what I can gather with a little research could be, MAP, MAF, TPS, O2, etc etc. Being as my MAP sensor CEL went away after fixing the issue with vacuum lines being flipped, I am starting to wonder if this all could be a result of the TPS. It would explain a rough idle, hesitation with blipping the throttle, and lack of power. We were able to get it started back up, we attributed it to it needing to prime the line, I was able to drive to a gas station fill it up, and then goto the store, It died on me again leaving and I had to get help to get it off the road, I did all the same things I had a couple hours prior and couldn't get it to start. I think my next course here is to buy a TPS, hopefully it doesn't get towed....

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puttputtinpup
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Posts: 10118
Joined: Sat Oct 08, 2005 5:18 am
Location: Winston Salem, NC

Re: 95 2.3L Rough Idle

Postby puttputtinpup » Thu May 17, 2018 11:35 pm

I'd double check to see if the fuel pump is providing enough fuel. As you're trying to start it, spray some starter fluid into the intake to see if it ones to life. If so, it may be starving for gas...filter, pump, etc
Currently P'up-less, but keeping my eyes open for a good deal
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