1990 Isuzu Trooper Emissions


Old 07-24-09, 10:10 PM
Thread Starter
Join Date: Jul 2009
Location: Oregon
Posts: 1
1990 Isuzu Trooper Emissions

For the first time my trooper just doesn't want to pass DEQ - high HC and CO. Autozone can't diagnose the car as it is older than 1995, and the local mechanics can only tell me it is an emission system problem. The Isuzu dealer has told me if the check engine light isn't on then they can't provide me with a diagnostic code.

I have replaced the EGR valve already but am wondering what else I should do? The truck just had a complete tune up - wires, cap, rotor, plugs. I was thinking of replacing the O2 sensor - but to tell you the truth, even with the Workshop manual and Haynes manual, I still can't figure out its location. Although they both mention it is screwed in to the manifold, there is more than one item that it could be - and neither of them look like the O2 sensor I ended up purchasing at the parts store.

Any help would be appreciated! Slow down the idle? carb adjustment? help!!!
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Old 07-25-09, 04:17 PM
Join Date: Aug 2008
Location: Massachusetts
Posts: 92
Have you tried the ol' "Seafoam injector cleaner in the throttle body" trick?
Disconnect the power brake hose at the booster, pour 1/3rd pint of SF cleaner into the hose (with engine running),shut off the engine, reconnect the hose, wait 20-30 minutes and start the engine. If the vehicle has been schlumping around town a lot, you'd be advised to do this at night.
Good possibility it'll clear out the problem.
You have to use Seafoam, though ( 6-7 bucks...)

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