Just changed my IMG

03-15-2010, 09:34 PM
Over the past year or so, my Rodeo started to idle rough and has an erratic idle. Went to many car forums and saw where these were a classic symptom of an IMG gone bad. After reading on line, using the Haynes manual, and using a copy of an overhaul manual I have, I decided to tackle this job this past weekend with my father-in-law.
The following are comments for anyone who is thinking of trying this in the future.

1. There are four gaskets that you will need.
∑ Throttle Body gasket:
∑ EGR gasket
∑ Intake Manifold gasket set (1 upper and 2 lower gaskets)
2. Everything is pretty easy until you have to get the fuel pressure regulator off. Every bolt on the engine that has to be removed are standard hex drive bolts except the 2 that hold the regulator on. For some stupid reason, Isuzu used at bolt with a circular head with a 6mm internal hex head. One of these is fairly easy to get off. Like other people have stated on this site, the bolt in the back is pain in the @#$#@ to get off. My father-in-law had a great idea that helped out. Put a 6mm hex drive bit into ľĒ internal ratcheting wrench. Note: tape the end of the bit before you place it in the wrench and it wonít fall out.
3. Upper Manifold can be removed at this point without much of a problem. You donít need the fuel injector tubing removed at this time but it needs to be unbolted from the upper manifold to remove at this time.
4. Removal of the fuel injector tubing from the hose wasnít really fun because after 11 years on the car, they were basically fused. Because it was so hard to get these lines disconnected, we thought we would just move the fuel line out of the way to remove the lower manifold. WRONG.

There are 2 bolts on the back of the lower manifold that attach a mounting bracket for the fuel line. We didnít know about these so as I lifted the lower manifold, my father-in-law reached below it and disconnected the fuel lines. This is the second pain in the !@#$#@$ because of the spring hose clamps Isuzu used. After about 30 minutes of trying to disconnect the fuel lines we finally got them disconnected. At this time, the lower manifold came right out and that is when we saw the 2 bolts on the back I talked about earlier in this paragraph. !@#$ us off not knowing about these.
5. Once we got all this disconnected, let it sit overnight in degreaser.
6. Putting the lower manifold back on, we decided to attach the fuel lines we removed to where they clamp under the manifold and then install the fuel bracket on the back. Let me just say, there is not an easy way to attach the fuel lines. Attaching the fuel line to the back of the lower manifold is by feel only.
7. After you install the he lower manifold you have the attach the fuel injector tubing to the fuel hose. They donít give you a lot of hose to place with so this isnít really fun either.
8. At this point everything is pretty easy until you get to the back bolt of the fuel pressure regulator. This has to be put in by feel also.
9. Once you get to this point. There is only about 20-30 minute left until you are done.

Here are some additional comments concerning this job

1. This took me about 4-5 hours to disassemble and about 5-6 hours to assemble (not including cleaning time for the manifolds)
2. Replaced all the spring clamps with clamps you can tighten with a ľĒ socket.
3. Although you can probably do this job by yourself, I would recommend this is a two person job.
4. Take off the hood so you can have better access. This makes it easier to get to all the parts. Only takes 4 bolts to remove the hood.
5. Take pictures as you go along. In case you forget where some hose or line hooks to, this will alleviate any problems with this.
6. Keep your bolts organized that you remove so you know which ones go back where.
7. Although I separated the throttle and the cruise cable, I donít think it was necessary. If you do, make sure you bolt it back where they were or you will have to adjust the throttle cable.

Anyway, after I got everything hooked up, started her and after a minute or so, ran like a charm without the rough idle.

I hope this helps whoever has to change their IMG.

03-21-2010, 09:14 PM
Just started doing this same job myself. And what a job it is. Where are the bolts that hold the fuel line bracket to the back of the lower manifold? Is it easy to access? This is the only thing holding me back at this time. Thanks.

03-22-2010, 06:59 PM

We had the same issue that you are having. The only way we knew about them is I had to use brute strength to pick the lower manifold over the 4 studs that attach it to the engine (hard but doable). Once we were able to get the lower manifold off the studs, as I held it up, my father-in-law un-clamp the fuel line from below where they come together. However, now that I know there are two bolts on the back side, I would suggest you get an inspection mirror and look at the back side of the lower manifold and you will see them. Once you find them, I believe you will have to get a socket on them by feel only to remove. I hope this helps.

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