1998 Isuzu Rodeo Poor Idle/Power loss/Serious backfiring

[kellercars]

1998 Isuzu Rodeo 92k 4wd 5spd

Bought it at dealers auction. It ilded poorly and I should have walked away. Must give it gas to keep it running. When accelerating or climbing hills it protests violently with backfiring and poor power. Very difficult to get to 50 mph. Diag from Midas says it mechanical. Compression check shows no bent valves. Runs rich--smell of unburnt gas. Any Ideas

Matt

[FL 3.2L]

CEL? Codes?

Have you tried pulling coils to see if pulling one leads to no change (bad coilpack)?

[kellercars]

CEL is steady in idle and blinking once the cars goes to bukin' and snortin'

Codes, I guess I trusted Midas that the computer knows nothing and that its mechanical.

Tried pulling one plug wire at time (with engine running) to see if I could detect change...no difference. Is that what you meant?

Thanks for response.
Matt

[Andie_J]

The timing belt slipped? Andie

[Gizmo42]

Take it to autozone and get the codes read for free. Then post the codes here and we can try to help you out. At this point it sounds like it could be timeing slipped as Andie said, badly broken intake gasket, coil packs, crank sensor, etc.

[FL 3.2L]

Might as well get a set of plugs. Sounds like they are getting fouled. I'd pull the timing covers, too, and see what things look like.

[kellercars]

Plugs look new but that don't mean jack. They are NGK

Previous owner (another used car lot) took it on a trade in. It was running really poorly so they brought it in to have a timing belt put on it. It did not fix the problem. I do not know if they replaced the tensioner. If the tensioner was worn out and the engine was put under a load do you suppose it backfire? I pulled upper timing belt cover and peaked inside. belt looks brand new. Can I check timing without pulling crankshaft pully?

I'm begininng to think that the poor idle and backfiring are unrelated problems. Idle problem may just be an EGR vavle or something, what do you think.

No Autozones in Palmer Alaska. We have only Schucks and Napa.

Thanks for your input and your time,
Matt

[kellercars]

So I bought a code reader and my rodeo spits out a P0300 generic. And it says "Random Missfire". Really does not narrow it down much.
Does anybody know about the timing belt tensioner going bad. I can't find a post on it, but a couple of people have told me that this is a common problem with these cars...Help?

Matt

[amigo-2k]

common cause of the misfire code and having to give it gas to keep it going is a leaking intake manifold gasket.

[trooperbc]

Originally Posted by kellercars

So I bought a code reader and my rodeo spits out a P0300 generic. And it says "Random Missfire". Really does not narrow it down much.
Does anybody know about the timing belt tensioner going bad. I can't find a post on it, but a couple of people have told me that this is a common problem with these cars...Help?

Matt

it's a common problem, but you don't have the symptoms, which are a LOUD KNOCKing sound, like a thrown rod. very loud. and if it's the tensioner will often disappear at ~2500 +/- i doubt this is your problem.

//bc

[kellercars]

Thanks for your input Trooperbc. I do not have a loud knocking but I do have noisy backfiring. I started it yesterday at about 10 deg F. and it idled perfect for about three minutes and then it started noticably missing. I sprayed carb cleaner around the intake manifold and got no response so I am wondering what the next step should be...EGR? Could it still be an intake manifold gasket or is the carb cleaner a pretty proof positive test?

Matt

[kellercars]

Figured I would check out the timing for myself and replace the tensioner while is was at it. Timing was set perfect. Replaced tensioner and the backfiring persists.

Next step will be intake manifold gasket and EGR...this sucks

[Cat Fuzz]

Backfiring from exhaust or throttle body? I'm thinking plugged cats or valve timing is still off even though you double checked it. Pull your pre-cat O2 sensors and see if it runs better. It will be loud.

I really doubt it's the IMG. Think about what a backfire really is. If its an exhaust backfire, the exhaust valve is opening late, while the piston is coming up in the bore and partially compressing the exhaust gases before the valve opens. If it's a throttle body backfire, the intake valve hasn't closed all the way before the spark ignites air/fuel mixture. Either way, it's still valve timing. Maybe a cam sprocket has slipped because a locating pin is sheared.

[FL 3.2L]

Originally Posted by Cat Fuzz

Maybe a cam sprocket has slipped because a locating pin is sheared.

This is happening with the crank gear key in 2.0L VW engines. Gets missed a lot. This would be the first I've heard in the Isuzu 3.2L. Is it becoming a common problem?

[Cat Fuzz]

Originally Posted by FL 3.2L

This is happening with the crank gear key in 2.0L VW engines. Gets missed a lot. This would be the first I've heard in the Isuzu 3.2L. Is it becoming a common problem?

I don't know. It's just something that popped into my head to explain the apparent correct alignment of the timing marks with goofed up valve timing.