Tune up help

[datrupr]

The check engine light came on the other day on my 98 Trooper. I took it to the local auto parts store to scan the codes and it told me I had a "random cylinder misfire" :gunt: . This immediately told me that I need a tune up. Now, on the Isuzu 3.5 engine there is no distributor and as I have never done a tune up on this type on engine before I was wondering if anyone here knows what I need to perform a proper tune up on this motor? Besides the plugs. The engine does not have plug wires in the traditional sense, it has what looks almost like solenoids over the spark plugs with a few small wires running from them to the computer. If anyone can help me out with this I would greatly appreciate it. Thanks. I have to have emmissions done this month and they will not run emmissions with a check engine light on.

 

[Brian McVickers]

The Chilton or Haynes books should tell you how to do it.
About $15 at Autozone.
Also check the web for Trooper forums that may have more detial.

 

[kevin]

You are right there is no distributor. The 3.5L is a direct ignition system, each cylinder has its own coil that sits on top of the spark plugs, the engine management system signals them when to fire. I like these systems as they are much more water resistant than a standard distributor. Replacing the spark plugs might cure the problem. Really, the only other tune up procedure that can be done is a valve lash adjustment, this is not an easy task, and depending on the milage and service history of your Trooper may not be needed. If you have records check to see if that has been done. Spark plugs are certainly a cheaper place to start, However if the valve lash is significantly misadjusted, it may cause premature spark plug failure. I have not yet had to replace plugs on my Trooper, so I am not familiar with the procedure for removing and replacing. If it is similar to other direct ignition systems it should be easy with a shop manual.
Good luck with the repair!

 

[Scott Brady]

My trusty Trooper went over 90k miles a few months ago, so I took it in to the dealer for the first time (the vehicle has never even required brake pads). I have done all of the scheduled services to date, but that is not much. Just fluids and filters.

The 90k mile service is a big one though, and I just didn't have the time:

The dealer replaced the plugs (good to 100k miles)
transmission flush and filter change
timing belt
t-case fluid change
injector cleaning
radiator flush
and that's it (over $1,400 though)

Oh, and a few repairs due to trail damage, like the tranny pan :Wow1:

I would recommend changing the plugs and having the injectors cleaned. The truck ran smoother, and responsiveness was improved.

 

[datrupr]

Ok, doing a little research and found that the Isuzu 3.5 really only needs to have the plugs replaced to do a tune up as the coil packs on the plugs rarely if ever go bad, and they are about $90.00 a piece. It is said to be a fairly dtraight forward job and the only difficulty, after removing the coil packs is getting to the #6 plug (drivers side back). I have also heard that the 3.5 does not like any plugs other than NGK or Champion. Apparently other plugs can sometimes cause the engine to idle rough or trigger a code on the computer......Strange. So, I am going to give it a go this weekend if I can't find a ride for DeSoto or the following weekend if I do. I will keep you posted in any regards.

Also, in my research I found that the Intake Manifold Gasket goes bad quite often and creates a hissing noise from the engine.... A sort of vacuum leak sound but no hoses are disconnected. Which mine is doing, and triggering "bank to lean" codes, which mine is doing. the auto parts store is telling me that the cat forward O2 sensors are bad. Before I spend $110 on new O2 sensors I will give the IMG a try for only about $40.

And, final notation, replacing the PCV increases power and mileage and only costs about $3.50 to replace. With the 3.5's propensity for oil consumption i have found that these get soiled fairly quickly and need frequent replacing. I will do this on my next oil change which should be around the middle of next month, and I will also give it the seafoam treatment, which I have heard many 3.5 owners swear by to help with the oil consumption.

Any thoughts on any of this anyone????

 

[flyingwil]

Just a quick note on the sea foam treatment... if you run it through you are going to need to change your spark plugs too :exclaim: Just don't forget that. All I have heard is great reviews in regards to Sea Foam, with the exception of the black smoke exhaust, and scared neighbors. Just my 2 cents.

Wil

 

[datrupr]

I did perform the required tune up on the Trooper over the weekend, and I have to say, this is by far the easiest tune up I have ever done. Just change the plugs and Bob's your uncle..... You're done. Miss fire code and all. It is running a lot better but the Intake Manifold Gasket is leaking and will be replaced this weekend.

In regards to the seafoam, I am expecting to have to change the plugs again afterwards, and since I am going to be doing this next month I opted for the less expensive plugs for the Trooper, not the platinum 100K plugs that should go in there. I just need to get the codes cleared for emmissions. That and to make it run better and be happier. When that is done, the platinum plugs will be going in, and I can look foreward to another 100k with out having to change them.

 

[Zaphod]

Ok, doing a little research and found that the Isuzu 3.5 really only needs to have the plugs replaced to do a tune up as the coil packs on the plugs rarely if ever go bad, and they are about $90.00 a piece. It is said to be a fairly dtraight forward job and the only difficulty, after removing the coil packs is getting to the #6 plug (drivers side back). I have also heard that the 3.5 does not like any plugs other than NGK or Champion. Apparently other plugs can sometimes cause the engine to idle rough or trigger a code on the computer......Strange.

This is all ABSOLUTELY true. I speak from experience.

The driver-rear SP requires at least one swivel attachment on the socket wrench. PITA.

As for the spark plugs themselves, the reason that non-factory plugs do not work is that the factory plugs serve both as an ignition source as well as a computer sensor. Wrong plug=bad sensor=engine light. Perhaps one of the other fine folks here know more specifics, but there it is.

 

[datrupr]

I was told that it was recommended that you use a swivel on the #6 plug (Back Drivers side). I do not have a swivel so I used three 3" extensions and pulled them out one at a time. Pretty easy too.

Do you have any experience on replacing the IMG?

 

[BajaTaco]

If you do end up replacing any O2 sensors, there is a place called URD that sells the Denso brand for Toyotas for $89. You may want to call them and see if they can get you one for Isuzu. I know their price is way better than the dealer and I will be getting mine from them.

 

[datrupr]

Chris, Checker actually carries the Denso sensors for the Isuzu for $56.00 a piece. I hve been informed that by replacing the IMG will clear the code. I am going to go the cheaper, yet more difficult, route first. If that does not work I will have no choice but to go for the O2 sensors. Thanks though. I will check prices there too.

 

[Zaphod]

Do you have any experience on replacing the IMG?

Negative. Don't even know where it is. :smilies27