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Eric, Automotive Repair Shop Manager
Category: Car
Satisfied Customers: 32537
Experience:  Automotive Repair Shop Manager, Technician/JA Mentor
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I have a 1990 isuzu trooper that had a loose exhaust pipe.

Customer Question

I have a 1990 isuzu trooper that had a loose exhaust pipe. it ran loud. then after a few weeks, it started idling up then down in neutral. now, I've secured the pipe, no noise or leak, and it starts but won't idle. it ran the highway, but if i idle, it dies. also, the starts have been sluggish just before I secured the pipe.
JA: Have you checked the battery, particularly the terminal connections? Are they corroded?
Customer: slightly,
JA: Are you fixing your Trooper yourself? What have you tried so far?
Customer: the bolts were loose to the exhaust pipe leading to engine. I tihgtened them, and replaced the gasket
JA: Anything else you want the mechanic to know before I connect you?
Customer: don't think so
Submitted: 1 month ago.
Category: Car
Expert:  Eric replied 1 month ago.


I am sorry that you have not been helped yet. I just came online and saw your question.

I need to know if it is the 2.6 or 2.8l engine

Is the check engine light on

Based upon the symptoms, I suspect either air intake leak, tp sensor or iac valve, but I need the above information to check a few things first

Customer: replied 1 month ago.
Hi Eric, Thanks for replying. It's the 2.6 four banger
Customer: replied 1 month ago.
I thought it might be the air flow meter, so i detached to see if I could run without... it did, but not very far :) so I re-attached and again, once I let it go to idle, it just barely hangs on below 1rpm then kaput. one thing i should mention is, it had trouble turning over each start for about three weeks leading up to this. and, after it ran for a while then shut off, the turn over was even slower, as if the battery didn't have enough time to recharge.
Customer: replied 1 month ago.
have no idea if above is related to idle-die issue... so when i had foot on gas, and running, it's like it's skippy, like the engine was sort of firing, but not all the way, then it would fire seemingly normal for like a block, or when going faster. anyway, prolly too much info here. lmk what you think
Expert:  Eric replied 1 month ago.


Ok, have you checked the fuel pressure yet. If not, we need to start with that

No vacuum to regulator ............................. 294 kPa (42 psi) at idle
With vacuum to regulator ........................... 245 kPa (35 psi) at idle

Customer: replied 1 month ago.
i'll have them check... i also wonder since i ran it with a loose exhaust pipe (close to engine) if I hurt the egr valve, or flamed the exhaust valves (or maybe intakes?)...
Expert:  Eric replied 1 month ago.


Possible that the exhaust valves are burnt, but I would expect to see the check engine light on due to severe misfire code they should set. You can have a compression leakdown test performed which will tell you that.

For the egr valve, remove the vacuum hose and see if it idles. Will likely be high idle, but if it doesnt die out, then the diaphram is shot on the egr valve.

Customer: replied 1 month ago.
I'll tell them and keep you posted
Customer: replied 1 month ago.
Expert:  Eric replied 1 month ago.

sounds good and you are welcome

Expert:  Eric replied 1 month ago.
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