Well I started it up again and took it for another test drive around the block.

And <img src="/forums/images/graemlins/frown.gif" alt="" /> itÆs worse. Now it doesnÆt idle up properly when cold. And power is very erratic. It surges slightly when accelerating and seams general unhappy.

So IÆm going to get a vacuum tester and a compression tester and go from there.
<img src="/forums/images/graemlins/frown.gif" alt="" />

Dose anyone know where the lobs on the the cam should be when itÆs at TDC compression for #1?

Well...all over the place but for #1, they should point down.

Did you re-check your valves?

If you are really sure the vaccum lines are OK, I would start testing the TPS and the MAF. Is it throwing codes? No CEL does not mean no codes.

After that, I would start back and make sure all the plugs are plugged in and well seated. Check those vacuum lines again and see if it gets better.

Michael

One other circumstance the O2 sensor is not in loop is on full acceration. Try flooring it and see if it suddenly takes off...I had an old Pathfinder years ago that went through 3 O2 sensors due to some bad gasoline from the refinery...got real familiar with the open-loop/closed-loop thang...

Ok, so I was going through my manual looking for pics of the vacuum system and I came across a pic that has a "manifold absolute pressure sensor (MAP)" labeled on it. It shows it on the back passenger side of the engine bay on the fender well.

And I donÆt have one on the Amigo. So what is it, and should I have one?

Also; could my issues be a ôfuel pressure regulatorö I see that in the same pic. Is there any way to check to see if itÆs working properly?

Dose anyone know where the lobs on the the cam should be when itÆs at TDC compression for #1?

On TDC of the compression stroke (of any cylinder) the cam lobes should be evenly offset to the opposite sides of whatever actuates the valve, somewhat like the ears of a cat.
On a SOHC with direct connect the cat's head would be normal (upright), but your Isuzu has cam followers in the mix so the lobes (ears) would be facing the head.

Ok I got a vacuum gauge and a compression tester. I tested the vacuum from the manifold with all the vacuum lines still attaceched correctly.

Findings;

At start up: did not idle up correctly, idle was low but stable.
900 RPM
12 to 12.5 in HG vacuum
With a fluctuation of .5 (seamed to be very stable)

After about 20 sec (without pushing on throttle) idle came up to:
1250 RPM
18.75 in HG vacuum
With fluctuation of .25 (again very stable)

After warm up (about 1 to 2 min):
1100 RPM
19 in HG vacuum
With fluctuation of .25 (very stable)

Ok so here is where it gets interesting. I manually added throttle, it reves up fine but then as it idles down it almost dies. Vacuum and RPM both drop to almost 0. Then I add a little throttle and it comes back up. I let off the idle slowly and it stables out at normally idle.

I can also here some odd sounds coming out of the engine. Really not sure how to describe it. The sound seems to line up with the firing of the cylinders, almost like a valve issue???

Three idle stages to control on a 2.6 (cold, base, and hot). All are controlled by different mechanisms. (aux air valve, thermal valve/FI soleniod, & air bypass screw via throttle body, respectively.) This is a great read on how to calibrate the above mentioned.
http://www.asashop.org/autoinc/feb98/techtips.htm

I hope I could help. I'm not sure if you have the vacuum routing, so here is a pic (88-95 2.6 non cali eq.)


Hope I could help. I'm sure there is a host of other things that could cause your issue.

Good Luck

Ok I got a vacuum gauge and a compression tester.

What was the compression? I am betting it is fine, but it is worth checking. And, did you (or have you) readjusted your valves?

Michael

I havenÆt done a compression test yet.

Question; Are you supposed to "manually" crank the engine over or use the starter?

And nope I havenÆt pulled the valve cover off since I installed the engine. So yeah I need to check the valve lash, and retorque the head bolts.

Anything else I should do?

IÆm also going to change out the front o2 sensor, the mass airflow, and the throttle body sensor. Since I have spars of all that stuff.

Don't go swapping parts yet. Failures in any of those would give you a code.

As far as the compression test. Warm it up (warm, not blazing hot), pull the plugs and crank it over with the throttle wide open. It is a good idea to pull the fuel relay or fuel pump fuse. Hook up the gauge to each cylinder and crank for a given number of cycles. I shoot for the 8-9 range per cylinder.

Other than that, I am out of ideas.

Michael