mel63

This is my first post - have been reading and researching for a few months. Been rebuilding/replacing 22Re in my 89 4WD truck. Have not owned a To since 1987.

Background: Long block from Oregon Engine Rebuilder's - Super Stock version (new head with RV cam). Installed LC Engr header with hi-flow Cat & Flowmaster 50 series. Have a LC Engr cold air intake. No other mod's at this time.

Started up after install - idles fine. When the pedal (throttle body) is pressed, engine responds, but there is a "hesitation" or surging in rpms. First thought is fuel pressure or fuel volume. ?? Maybe the ECU or throttle position sensor???

Before chasing the gremlin,thought I would ask all of fine mechanics for advice and /or insight.

Thanks,

thook

Assuming your ECU is clean, I would blame that last.

New fuel filter? How old is the fuel pump?

Throttle sensor is a possibility. Then, so is the air flow meter. Are you familiar with the factory service manual? TPS (adjusted correctly?) and AFM testing is a good place to start, if you can rule out the filter and pump first.

Note: There is a test for the TPS and AFM not covered in the manual that can keep you going in circles, if either one of them is actually an issue. Roger Brown (aka 4Crawler) has a website covering TPS adjustment and testing with this "uncovered" TPS procedure in addition to the standard FSM one. And, if you search "AFM testing" using "thook" as the thread author, you'll see a method for the AFM. I'd basically used the same method Roger Brown did for the TPS coined as a "sweep test". You see, either component can test fine according to the FSM, but the sweep test actually troubleshoots along the electrical track as either the throttle moves or the meter flap. Bad spots can develop along there, but the FSM procedures won't find them.

mel63

Mathew,

Great advice - thanks. Have the FSM of rthe truck - awesome reference.

Fuel filter is new. Just replaced with new engine. Fuel pump ???. Assume it is the original. That's why I suspect it.

Will get the 2 procedures and do some testing tonight.

On a side note - what part of Ark you live? We use to vacxation in Mountain Home & Eureka Springs. We lived in N Louisiana for 7 yrs.

Love the state of Ark.

Thanks again.

Mark

mel63

Thook,

Just wanted to let you know....

We looked at the great articles you refered us to. Discovered that the TSP was bad. Replaced and is running great.

Thanks again.

Mark