Alright, need somebody who knows 22re's better than myself. Swapped in a used motor into my '87 after my original lost a timing chain in the spring, but have run into an issue. Truck will not rev past 4200 rpm at WOT. It feels much more gutless than my previous motors, but it is bone stock as well.

When driving, I can get it to approximately 4500 rpm at about 75% throttle. Dip any deeper and it falls apart, dropping back to 4k and acting like it's on a rev limiter. At wot at any rpm it feels like it has less power than at 75% throttle. Under no load it will make it to 5500 rpm at 75% throttle. Dip further into the throttle and it falls on its face, breaking up and bouncing between 4000 and 4200 rpm. It idles OK, about 1k rpm with the occasional miss, just is not fun to drive.

I have checked and adjusted the TPS, tested the AFM, changed plugs, wires, cap and rotor, and all the same. No vacuum leaks, fuel system is clean, I am at a loss.

Anybody have any suggestions?

 

Checked your fuel pressure? Sounds fuel related since it only happens under load

 

Sorry, I missed a line in my first post.

It will only reach 5500 rpm at partial throttle. Once you dip past about 75-80% throttle is when it breaks up and falls back to 4000-4200 rpm. Back off the throttle and it will clear up and rev back to 5500 rpm.

 

What condition is the engine in? How many miles?

 

150k miles. Compression is spot on,and it passed a leak down test.

 

Fuel pressure, like JasonYota suggested? Have you given the EGR system a check?

 

Wow and I thought I was living dangerous when my rpm hit 3000.

If it is not the fuel system you did install a new filter when you changed engines??

How do you know the fuel system is clean ?? Is every thing new??

Pinch or crush a fuel line changing engines??

How many miles on the fuel pump ??

Could be electrical

Circuit opening relay dropping out.

Ecu not firing the injectors or not changing the timing

 

New fuel pump and filter, all lines were cleared when I swapped motors, and I have changed out the FPR. Injectors were cleaned locally before the motor ever turned over.

Timing is spot on, everything points to a bad TPS but it's throwing no codes, and when I test it by 4 crawlers method, it's in spec. Load or no load it does the same thing.


I'm used to being able to wring these motors to 6k without much issue. It drives OK on the road, but without the ability to wind it out I won't be taking it to the dunes in a couple weeks. Also makes Highway merging a bit hairy.

 

I wonder if the coil is getting weak. It is an easy check to do in the Haynes Manual. I have had two to fail on me. Just went thru another AFM this week and it is an easy check to do as well.

 

Did you check for a smooth rise in resistance between the VTA and E2 contacts of the TPS? Seems like you probably have, but might as well be thorough.

 

I did not originally, but just checked it out and am not getting a smooth increase. It's all over the place. I have a few spares I will check out and compare results before I swap them.

 

OK, update time in case anyone has a similar issue.

Tossed another TPS on the truck that had a smoother transition. No difference. Changed the brand new fuel filter just to be sure. No difference. Checked fuel pressure, was perfect. Everyone I spoke with said it still had to be fuel related. I had spare soft fuel lines so I swapped those on thinking maybe one of the lines got kinked during the motor swap and was still collapsed. Once again no change. I had it to the point where I was into the fuel rail and that was all that was left. Before I got into that however, I wanted to check out another suspicion.

On a gut feeling I pulled the valve cover to see if the timing chain was off, and bingo. Cam gear was off by two teeth. Pretty amazing that it was off two teeth, and I was still able to time it, and that it still had pretty good drive ability below 4200 rpm and was getting a solid 20mpg. She's all good now though, drives much better and seems to run a bit quieter. I just wish I had adjusted the valves while I was in there.