95 2.3L Rough Idle

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sevlor
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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
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Posts: 15
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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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

sevlor
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Isuzu vehicle(s): 1995 Isuzu Pickup Regular Cab

Re: 95 2.3L Rough Idle

Postby sevlor » Mon May 21, 2018 2:07 pm

So I will be changing out the fuel pump tonight, Saturday I hooked up a fuel pressure gauge in line and the needle didn't budge. I am also going to go ahead and replace the TPS and the pressure regulator as I have those parts coming in as well. All the work tonight will be accomplished in a Wal-mart parking lot with removing the bed.

sevlor
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Posts: 15
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 » Mon May 21, 2018 9:50 pm

Removed the bed liner and found out I didn't need to remove the bed, previous owner had cut an access hole. I used this and got to the fuel pump which was definitely failed. I replaced it and got the truck running again, but I still have the rough idle once the truck is warmed up, and it seems to be running rich based on how the spark plugs look. I have the TPS and fuel pressure regulator still coming in, I am hoping one of these fixes the issue otherwise I am out of ideas.

sevlor
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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 » Tue May 22, 2018 9:12 pm

Got my new TPS in from Rock Auto today, took the throttle body off in order to replace it, and this is what it looked like:

Throttle Body.jpg




I cleaned it best I could with throttle body cleaner, went ahead and cleaned the MAF, installed the new TPS and put everything back together. It is a night and day difference than how it was running all day today, with it switching between code 44 (Running lean) and Code 45 (running rich) and wanting to die at stop signs unless I put my foot on the throttle a little bit. I took it out for a drive and I am able to accelerate with no problems where as before I would feel like I hit a throttle limiter. I still have the problem where if I blip the throttle it will hesitate, so I am wondering now if I just need to pump a bunch of injector cleaner through the fuel system as well as give it a full seafoam treatment.

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puttputtinpup
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Re: 95 2.3L Rough Idle

Postby puttputtinpup » Wed May 23, 2018 7:26 am

I would think that with a fuel injection system, there's gotta be an IAC (idle air control) valve somewhere.

sevlor
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Isuzu vehicle(s): 1995 Isuzu Pickup Regular Cab

Re: 95 2.3L Rough Idle

Postby sevlor » Wed May 23, 2018 8:00 am

If there is one I can't find it, Rock Auto doesn't even list one for my truck, the chilton's shows that if it were to have one, it would be on top of the throttle body. As I stated above, I seemed to have fixed my idle issue, probably in total combination with everything I did (throttle body clean, TPS, and MAF clean) all I have left from a problem stand point ; and it isn't as bad as it was; is the slight hesitation when you just blip the throttle.

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Quahlity
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Isuzu vehicle(s): 1992 Isuzu pickup 2.3 carb

Re: 95 2.3L Rough Idle

Postby Quahlity » Sat Jun 02, 2018 9:42 am

On my carb'd 92 pickup, I had a similar problem. It ran badly most of the time. Even on it's best day, there was this one long hill where at the bottom it stalled every time. On the days it ran better than others, it still might stall at any stop light. Not ideal. My problem was the truck had sat for a a very long time (like years) and during that time, the ethanol in the fuel had separated into gas and a water/ethanol sludge. The sludge could get through the filters, and would not play well with the carb. In my case I had to drop the tank and clean it, as well as the carb countless times. I'm not sure what to suggest with FI, but if you keep having problems that don't make sense, it might be related. After I found and fixed that, the truck runs great.

sevlor
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Posts: 15
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 » Tue Jun 05, 2018 2:15 pm

I have been driving it the last couple weeks with no problem, ran seafoam through the vacuum systems, and lucas fuel system treatment through a tank of gas, and its been running great now, still has hesitation when you blip the throttle, but other than that, it's been running really well. I now need to flush the coolant, replace the timing belt, and then get all the drive belts put back on, currently the only belt hooked up is to the alternator, the AC has been unhooked since I got it and I am wondering if the previous owner did that in trying to diagnose these issues

heroZombie
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Isuzu vehicle(s): 1995 Isuzu pickup S 2.3

Re: 95 2.3L Rough Idle

Postby heroZombie » Thu Jul 26, 2018 1:36 pm

I had this issue when I first got my 95... I ended up putting several fuel pumps on before finding a bad ground wire to the pump but only after hooking up the fuel pump to a toggle switch on my dash as an anti theft almost, if some one cut into the bed of yours they had to replace the fuel pump probably a few times to figure out the hole was easier than removing the bed lol. I’d like to see your vacuum lines please I had a rats nest on top of my canister and they chewed up everything please send me under the hood pics real close the the canister

sevlor
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Posts: 15
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 » Tue Aug 07, 2018 8:42 am

I will get some pictures up of that as soon as I can, I don't keep the truck at my house as I don't have the space, so I keep it where I work, and don't drive it all the time.