So I have a 91 toyota 4runner with the 3.0 Motor, Its been running sluggish lately, (yes i know the 3.0 motor is sluggish to start off with), but it idles great, then when I give it gas, it boggs down and chugs, and will go, but I feel the gas pedal is pressed pretty hard, and it not a smooth ride.

No Check Engine light, so I did the basics, new airfilter, new plugs and wires. Still does it. Any thoughts?

 

Have you checked for ECU codes? You can have codes stored that don't trip the Check Engine light. How's your fuel mileage? How many miles on your O2 sensor?

There are so many things that can fit the "sluggish" moniker, we need more information/specifics to troubleshoot without just telling you to throw parts at it~

 

Fuel Filter and Injector cleaning is also a good place to start, assuming they have not been done recently.

 

If you have a Toyota service manual (or download it from the sticky) you could check the specs on your air flow meter. I had a similar issue with my 3.0 and it turned out I had a defective air flow meter.

 

A 3.4 swap will eliminate your sluggish 3.0 problems haha.

Id also check your catalyctic converter.

 

1 fuel filter
2 air filter
3 egr valve
4 dirty objectors
5 cat converter

 

Here's the senario. It starts right up and idles perfect, when its warm about 850 rpm. It doesnt miss or anything at Idle. When I go to drive it, or put a load on it, it hesitates, and surges. Big time, enough I feel I shouldnt drive it.

2 days ago when I posted it, I changed the spark plugs and wires, cap and rotor, and airfilter.... NO difference.

today,I ohmd out the tps per fsm and all ohm's were within tolerance. Ohm'd out the AFM, same thing all connectors in ohm tolerance. here's what I have found today..

The distributor, is adjusted pretty far to one side, if I adjust the distributor (line up the markings on the block and the dis shaft, back to starting guide, the response seems to be a little better, but the timing says its like 20btdc, makes me want to think the timing belt may have skipped a tooth? also when I did the timing, the computer throws code 51? Switch Condition Signal?? code?

I have not changed the fuel filter, which Ill do tomorrow.

Has anyone ever had a fuel pressure regulator go out? if so what where the symptoms?

 

Fuel pressure reg going bad means terrible performance

 

I would reccomend a compression check just for piece of mind.

I had this issue with my old 3.0 and it turned out to be a completely dead hole. No fluids mixed or anything

 

May be newb recomendation but couldnt hurt and wont cost anything.

I have heard that the circuit open relay (COR) is in a bad spot on these trucks and is subject to corrosion. Take a peak for piece of mind.

Corrosion= High Resistance= Less Voltage to Fuel Pump= Runs like ˟˟˟˟˟.

 

Are you bridging TE1 & E1 in the diagnostic port when you check the timing?

 

check the cat, see if its clogged.

 

Check for vacuum leaks, especially around the big black rubber intake hose where it connects to the throttle body. They all develop big cracks toward the bottom that are hard to see unless the clamp is removed. Big amount of unmetered air could cause all kinds of problems. To check for other leaks, take a can of starting fluid and spray around vacuum hoses while running. If it chokes out, you've hit a bad hose. Just hitting some of the easy stuff first....

 

I should have read this... My distributor is in the middle of it's adjustment block. I suppose your jumped TE1 and E1 and verified the check engine light was flashing when you checked your timing?

 

Yes te1 and e1 was jumped, only when it was jumped code 51 flashes. Usually in diagnos mode you can hear the rpm change, not in this case? I'm going to check the code out today and fuel filter

 

Code 51 AC signal on; DL contact off (in trany shifter with diagnostic connector jumped)

 

Check your compression, these motors are notorious for burned valves. I know 3 friends including myself with burned valves, and one has had it twice within 160,000.

 

So just wanted to give everyone the answer to the original question... There was actually 2 things wrong at the same time first and most severe was the catalytic converter was totally shot and clogged. Put a new cat on was like it had a whole new motor! The second thing was the TPS sensor was not working. When the tps sensor goes out, another symptom was it wouldn't let my ECM go into diagnostic mode, therefore I couldn't set an accurate timing. It was throwing code 5-1

 

Yep new cats can make a world of difference