1JZGTE Intermittent Problems - Hard to start/Stalling/Over-Fueling/Under-Fueling

[rtrona]

Hey guys,

I am about to purchase a 1991 MX83 Cressida, which has had a 1JZGTE conversion from a jzx81. The car engine/driveline is all factory jzx81 items, and uses factory ECU. Vehicle is auto. Has SITC and SAFC.

The car is previously richzx's, and AFAIK (according to the build page) was wired by Mos. However the seller has mentioned it has an intermittent problem where the car becomes hard to start, when it does it over-fuels, sometimes under-fuels and will occassionally stall. Then some days it runs fine. The conversion has been done for some years, but has had the problem for the last year.

The ECU has had the capacitors changed, and have also tried a second ECU. The owner has plugged in a scanner for fault codes and the only thing present was relating to the coil packs. Which were then replaced, with still no success. Could this be a fuel pump issue? It utilises a Walbro GSS294.

I have searched google, toymods, supraforums everywhere, finding simular issues which all point to leaking caps in the ECU, but having had them changed, and a second ECU to try it still did not fix the issue.

Has anyone else experienced the same thing, has anyone else got any idea's? Would really like to get the issue sorted so i can attempt to drive the car home!

Thanks in advance!

[richzx]

I would say coil packs are gone or it may need a fresh set of plugs. I would set the sitc and safc to zero unless they have been professionally tuned on a dyno as i only had a minor fiddle with them. It is either a fuel or spark issue and I would start with spark. How do you know it's under fuelling? I think you will find it's over fuelling when it's turned over quite a few times and doesn't start. Also check the ignitor is not on the way out. HTH.

[rtrona]

Coil packs have just been replaced with new ones (surefire?). It started today apparently, after sitting for about 3 months. Running very rich. Blowing alot of smoke (fuel). Jake diagnosed it 'under-fueling' by it missing on boost, doesnt blow smoke when it misses on boost either (dont know if that helps) engine light is also apparent.

[pandaah]

ecu caps? open up the case nd have a look

[rtrona]

Ecu caps have been checked. And previously replaced.

[richzx]

If the engine light is on then you should be able to get an ecu code to tell you what the problem is. If it's been sitting for 3 months then expect it to blow some smoke when first started. As i Said I would set the SITC and SAFC to 'o' for all settings as the timing and fuel may not be right. The ecu caps have definitely been replaced so you are all good there. Missing on boost sounds more spark related than fuel as the factory ecu gives you bucketloads of fuel. Still check the coilpacks if they are those new red ones I have 'heard'they are not as good as Toyota ones but I don't know if that's correct or not. Get the codes and see what that tells you.

[rtrona]

Thanks for the reply's, I now have the car in my possession, and have only had the issue once with it. Mind you i have only driven the car 3 times no more than 5km each time. It ran fine, i turned it off. Started it, idled rough, engine light on, revved it a bit, missed, ran rich and then popped out the exhaust. Turned the car off and then turned the car on, it was fine.

I have purchased another ignitor (waiting on it now) and also some coil pack connector clips because there are none on there!

Will update once these are replaced, in the mean time if anyone has any other suggestions. I will also set the SAFC/SITC to zero.

Cheers

[rtrona]

Still waiting on the ignitor, have set the SAFC & SITC to Zero, hasnt changed it. Once the car finally does start after a lot of cranking it runs like its only on 3 cylinders. Plus you cant hear the fuel pump.. might be something else to look into if the ignitor doesn't fix it.

[Slim]

Often, when super cold, my JZX81 engined MX83 starts very poorly. It's clearly overfuelling given the amount of fuel smoke coming out the pipe. When it starts like this it takes a lot of cranking to start and then runs like it's on 3 cylinders for about 10-20 seconds before the fuel is cleared and it picks up, then runs fine.

It runs perfectly at all other times.

I also have had the ECU caps replaced and have new plugs.

[rtrona]

Thanks for the reply! And yes being in Tasmania it's always super cold here! It occasionally after alot of cranks will pop out the exhaust. But won't fire.

[rtrona]

The other ignitor has not fixed the issue. The only difference between them is the new ignitor has a noise filter? capacitor? Just a grey 2 pin plug off the side of it. Part # 90980-04083 250/0.47.G. I read that this doesn't need to be plugged in. Can now hear the fuel pump also. Wont even fire now :-( with the new or old ignitor.

Would the coolant temp sensor be worth replacing? The green plugged one that runs to the ECU?

Just in regards to the coil packs, they are super spark. Have had a bit of a browse through the net and haven't encountered anyone having any problems with them

[rtrona]

Righto, checked for fault codes and am getting fault code 31. Which according to Cygnus X1 Home Page it relates to the MAP sensor or ecu? Checked the ecu the caps are still all good. Getting power to the MAP sensor. Guessing i will replace it? do they cause an intermittent problem?

[rtrona]

Replaced the MAP sensor and still no luck, i checked the voltage to the PIM pin on ECU, and got 2.65volts with engine off (which is about right), although it went up to 3volts when cranking...

[CrUZida]

May as well try a new green ECU coolant temp sensor, they are about $60 for an aftermarket one from Tridon.

[rtrona]

Do you know the part number for the tridon temp sensor? Repco cant seem to find one.. Also does anyone know what would cause it to go up in voltage when cranking? its meant to drop correct?