Rebuilt 1JZ won't accelerate properly

[Sam]

The TPS is set to dead center and does not look to be tampered with. There is still white paint marking when it was set from factory. He changed the spark plugs but has not yet started the car. He wants to have it nice and cold to see how it will start, seeing as that's when it tries to flood itself. So far the only change from the last time I was able to drive it is the new spark plugs. Fuel dampeners in and the fuel pressure is 38-39 PSI.

So he rolled it outside today and will start it when it's brisk out tomorrow morning. I hope for some magical reason, it will just run fine! I'll give another update tomorrow when I go for a visit.

 

[IBoughtASupra]

Hmm, I usually see Toyota TPS marked in yellow from the factory.


On the JZ motors, cold start is controlled by the ECU, unlike the 7M where it has a cold start injector switch, the JZ's don't have one. Have you replaced the ECU temperature sending unit? Not the spade connector looking one, I am talking about the two pin green plug sensor on the waterneck.

We all know coil packs go bad on JZs after all the year, have you looked at that and checked their resistance and see if they were putting out a good spark?

 

[Sam]

I went in today, but the mechanic had left early. My car was still sitting outside so I looked inside. It looked like he hooked up the old Blitz Access ECU, so I assume it still did not want to run properly. I imagine he's starting to think something is up with my stock ECU now and wanted to compare how it ran to the Blitz unit. Although he has opened the stock one to check out the circuit boards and they appear healthy.

I'll go back tomorrow and tell him about the ECU temperature sending unit and testing the coil packs. Thanks for all the input IBoughtASupra! I appreciate it!

 

[IBoughtASupra]

No problem. Keep us updated.

 

[OneJArpus]

i had the same exact issue with my car regarding driveability when i first completed my 1.5jz swap, i put on the DM by-pass hose and did a full swap. I would sputter at the 2600 mark so bad that it would not go past 2600. I put the FB @ 43 PSI no vac and it would drive fine but still get the hesitation @ 2600 RPM, i purchased a new damper and the problem went away. Car ran fine, my AF/R was in the 9's 10's when cold w/o damper and then would rise to about 12-14. Now with damper its at the 13-16 mark warm n 10-14 cold, i say put the damper back in or get another 1, and tell him to mount the FPR so the return line is facing down (not sure how much of a diference that would make but i've never seen it mounted sideways)

 

[Sam]

A new dampener is worth a shot I suppose and since mine was clogged up previously. Where do I find a brand new dampener? A 2JZ one from Toyota would work, right?

 

[Sam]

It seems the mechanic took the Blitz ECU home with him and attempted to resolder as many connections as he could, and managed to replair the ECU! I couldn't believe it. The Supra was sitting outside and it was only 1 degree above zero Celsius, so it was nice and cold to see how it would start. Low and behold, it started without drama with the Blitz ECU, which was previously not functioning. It was late when I got there, so I not able to see how it drove. He's going to drive it tomorrow to see if it still sputters and misses under heavy acceleration.

So, I wonder if the ECU that was sold to me on Supramania is a dud? I guess we'll find out on Monday when I go back to see the conclusion. The mechanic is suggesting also that I send these two ECU's to Driftmotion's ECU repair service.

 

[IBoughtASupra]

Hope it is fixed.

 

[GrimJack]

As for the damper, it's worth replacing if you still have the stock unit, and a new one from ATI isn't expensive. I've seen quite a few of the original ones fail by now, they just aren't mean to last 20+ years.

 

[Sam]

I forgot to mention that while idling cold, it was still pretty rich. The meter displayed 10.0-11.0 air/fuel ratios. And it still sputted a little now and then while idling, but it was much improved from before. I didn't stick around long enough to let the engine warm up to see if the fuel mixture would even out.

If I was a betting man, I would guess that the 1JZ will still have issues running. I'll update again on Monday.

 

[IBoughtASupra]

Now you have it idling, get another fuel dampner and put it in there and see if it help but if what your mechanic did to the ECU helps, send it to Aaron and see if he can repair it.

 

[mk3tattoos]

As far as A\F's go, your ecu needs to learn itself, so it takes some driving before it will be normal.

 

[Sam]

Quick update from my Android phone. The mechanic is busy with old ladies minivans, so he hasn't really done anything. He said he started it on the weekend once and it was fine. So he is going to assume when he takes it for another test drive, it'll be good. Its not throwing any codes, so he does not believe it to be any malfunctioning sensors. He thinks giving the Blitz ECU time to learn will improve the Air/Fuel ratios. I hope he's right. He will give the stock ECU an inspection later on. I update again on my next visit to the shop