97 3.4 swapped into a 90 toyota pickup. My issue is that coming from a stop when I go to give it gas truck will stumble/hesitate on take off untill I get up over about 1000rpm. Truck runs fine when driving just a bad hesitation on take off. Only does it when it's warm and it's very intermittent. Sometimes I'll shut it off to go to the store come back out and start it up and it will be fine. What I've done so far(cleaned TB and iac valve,cleaned maf,new fuel filter,new plugs and wires, new downstream o2 sensor,new cts) tested maf and seems to test fine from what I can understand from the Chiltons book. Tps seems to test fine. Only codes I have is that it's running lean and the cam position sensor. Tested that and it tested good when cold but when warm it tested at about 1370 ohms. Looking for ideas.

 

When you say "stumble/hesitate", do the RPMs jump up and down when the pedal is press a certain distance or does it take a bit for the car to speed up? Have you checked the throttle cable that runs from the throttle body to the transmission? Does it have any excess slack when you try to lift it from the actuator lever that opens/closes the flap?

If you are running lean it could be a bad/dirty injector or possibley a bad fuel pump

 

Cam sensor is still within specs .

That is not to say you might have a corroded pigtail

Even a loose fuse in the block could be your issue

Make sure the ECM grounds are good it should be on the left side of the intake manifold .

I have had to run them direct to the battery to clear up some issues.

ECM not getting wet at all??

 

I'm sorry for not clarifying but it's a 5 speed and when I say it hesitates when I go to pump the throttle it feels likes its choking. Sometimes it will stall taking off from a stop light. Throttle cable looks like it has a little slack not too much, nothing that I would think could contribute to the issue.I suspected a dirty injector, I'm on my second bottle of injector cleaner, the first was sea foam now I tries Lucas.

 

Ecm grounds are good I checked those. Maybe I'll run a wire from one of those grounding points to the battery see if it helps.It could be a bad pigtail, I never really thought about that. If the computer itself is not grounded will that make a difference? Currently it's laying on my floor,everything's plugged in Ive just yet to have a chance to mount it after the swap.

 

To clean the injectors, use some Chevron with Techron. It does a better job than Sea Foam. B12 also works well.

 

It grounds through the harness .

Then having it bouncing around on the floor is not helping .

Pins could make intermittent contact.

I went through 3 ECM`s getting damaged by water till I mounted mine to the bottom of the heater box.

A few years now no problems.

 

I tested the tps again and vta-e2 came out to 3.2 idl-e2 was 0.49 no matter what thickness

 

Tested the tps again vta-e2 3.2 no matter what thickness I put between the stop screw it never came down into spec according to my book. I'm guessing this is for my truck,my tps only has 3 pins though

 

Has it ever run well? Or did you just now get done swapping? Did the motor run fine before swapping it? It's usually an error in wiring no matter how thorough you think you were.

 

It's been done for about 3 weeks now and has done it since I finished it. Shouldn't be a wiring issue I had the wiring done by Toy only swaps so it was pretty much plug and play

 

Ah, good to know. You need to call them for sure. They owe you some tech support since it's not running properly. Do you know the motor ran well before you installed it? You sure you don't have a big ol vacuum leak? Cam timing could be off a tooth or two too. Done the timing belt recently?

 

Does it run perfectly fine until it warms up?

 

Yes once it warms up it usually begins to hesitate on take off. Timing is good and I checked for vacuum leaks and came up with nothing

 

Sounds like it's starting to fault in closed loop, so start with those sensors. Cam and crank sensors (make sure your cam sensor is even plugged in.... done that before), front o2 sensor, maf. Make sure your fuel pressure regulator is plugged in properly too.

Is the obd2 hooked up? Codes?

 

Yes only one I had was cam position sensor but I tested it and it came back good. Once it warms up it tests at 1380 but that's on the upper end of the spec. Tps didn't test right according to the book. Not sure what the specs are to test the o2 sensor

 

First off- I have changed a bad crank sensor that measured out perfectly in spec. You have actually taken the timing cover off, put the crank at TDC, and saw the cam marks lined up? I mean with your eyes, not a timing light.... The ECU can account for retarded or advanced timing by adjusting spark timing, so timing light doesn't tell the whole story. If you got a camshaft position sensor it's either a bad sensor, or out of time. Or the cam sensor isnt' even plugged in (done that too)

 

When I did the valve cover gaskets when the motor wasnt In the truck yet I checked the cams when on tdc it's all good. I unplugged the cam sensor when running and noticed a difference in performance idk if that's a good way to tell if it's good. Tested the downstream o2 sensor came back at 13 ohms and the upstream was 14 ohm which is way out of spec according to my book