ANOTHA ONE - non-vvti 1JZ-gte out of a JZA70 breaks up under WOT ""HELP MEEE""

[jdesign]

So This is going to be long, but I am really running out of ideas so I really could use some experienced input.

I have a BWM E30 that I swapped a non-vvti 1JZ out of a JZA70 into. Right now the motor is basically stock running a stock ECU. It does have a K27 in replacement of the stock twins. The car runs, and drives fine under 4500 but once I build boost under wide open throttle, it breaks up or hesitates. It sounds like fluttering sound and I can tell the car is lacking power. If I build boost under 50% throttle it seems okay, but under WOT it breaks up. It doesn’t fall on its face like a fuel cut, but more like a misfire.

I have tried a list of items I thought could be the culprits but come up empty handed each time.

• Ignition problem caused either by plugs or coil packs.
o I replaced and re-gapped my plugs to .028 (I also tried gapping them smaller and wider without a change .020-.035)
o I swapped out my ignitor with one from a running and driving car
o I swapped out my ECU with one from a running and driving car
o I swapped out my coilpacks with a running and driving car making way more boost than me
o I also did a resistance test on all of them to confirm they were all in great condition
o I bought NEW OEM Denso coilpacks anyways
o I have new Coilpack pigtails

• Fuel system- I thought this was the issue, So I was running a walbro pump and had the stock 1jz FPR and rail with OEM 380cc Injectors. My wideband says I was running extremely rich which was confirmed by the amount of fuel I was consuming. I read another guy had the same issue and his fuel pressure was at 100psi. so this is what I did:
o I have a brand new walbro 255
o Installed a brand new aeromotive fuel pressure regulator and added a gauge and adjusted the pressure to 43psi at idle
o Checked the return line and tank vent for blockage
o I installed another fuel rail with the same injectors
The car seemed to run wayyy better with the pressure under control, but it still breaks up the same. I tried turning the fuel pressure up and down +-15PSI to see if this would affect the break-up, but it seems like that’s not the issue.

• I did a visual inspection of all my couplers, which are all new, all connected, no holes etc. Not to think that this is the problem but will be doing a leak test to confirm later on.
o I have a manual boost controller on the car as I want to diagnose what the hell is going on. I can only turn the car down to 6PSI. It will build boost to 6psi but once it starts breaking up under WOT, the gauge reads from 4-6PSI.

• The wide band is reading 15’s when I am cruising and will be 10’s-11’s under throttle
o I have a new O2 sensor

• Adjusted the TPS with feeler gauges to the exact spec
o bought a new TPS sensor just in case even though the old one tested okay

• Swapped out the MAP sensor with the same results across 3 different sensors
• Swapped out the Idle control motor with the same results

o I installed a NEW air intake temp sensor
o I installed a NEW TPS sensor
o I installed a NEW O2 sensor
o I installed a NEW Coolant temp sensor
o I installed NEW Denso coilpacks
o I installed NEW spark plugs
o I installed a NEW coil pack pigtails

**UPDATE**

o The coil pack polarities ARE correct
o ECU swapped and drivability improved. With the first ECU connected it just dies at idle now, where the other one is fine. but the main problem remains.


I also pulled the entire harness out of the car and inspected it for any broken, stripped, or exposed wires. All of them were replaced or checked out just fine.

• At this point I am kind of stumped. Im just wondering if there is anything obvious I am missing that would cause this? PLEASE HELP!

[Daddio]

Are the coil pack polarities correct? (ie all the same, but remember they are not mounted the same way around)...had a similar issue when one coil pack had reverse polarity after someone changed the coil pack plugs. (No idea why a reversed polarity coil pack would do this given its just a coil, but it did) Nice & easy to check

[big_zop]

While its a shame that you are having issues, the engine bay definitely looks neat.

My suggestion is based around the throttle cable, it doesn't look straight in that picture and checking against my car, it isn't using the same bellcrank either. The reason for this is that the throttle actuator usually has provision for external devices (auto kickdown and cruise control) and it appears that you have picked up the one that normally is used for cruise. Now if you check you get full throttle then I am sure it isn't an issue but I would at least make sure that it runs straight and if you want to put it on the right one then its the next one over (I cant quite see it on your car but if it was manual originally, then it may not have the auto kickdown which will be past the main throttle cable and rotated 180deg).

As a last resort and having checked out as much as you do, it might pay to get it on the dyno to have it checked out. While a big single on the standard ECU isn't going to cause you breakdown problems, it would pay to have it checked out and hopefully they could give some insight to the issue you have.

[jdesign]

Are the coil pack polarities correct? (ie all the same, but remember they are not mounted the same way around)...had a similar issue when one coil pack had reverse polarity after someone changed the coil pack plugs. (No idea why a reversed polarity coil pack would do this given its just a coil, but it did) Nice & easy to check

This is worth checking I guess. It doesn't seem like its running on 5 cylinders which is what I would assume this would do, but I will check it and report back.

While its a shame that you are having issues, the engine bay definitely looks neat.

My suggestion is based around the throttle cable, it doesn't look straight in that picture and checking against my car, it isn't using the same bellcrank either. The reason for this is that the throttle actuator usually has provision for external devices (auto kickdown and cruise control) and it appears that you have picked up the one that normally is used for cruise. Now if you check you get full throttle then I am sure it isn't an issue but I would at least make sure that it runs straight and if you want to put it on the right one then its the next one over (I cant quite see it on your car but if it was manual originally, then it may not have the auto kickdown which will be past the main throttle cable and rotated 180deg).

As a last resort and having checked out as much as you do, it might pay to get it on the dyno to have it checked out. While a big single on the standard ECU isn't going to cause you breakdown problems, it would pay to have it checked out and hopefully they could give some insight to the issue you have.

Thanks! It looks even better now without the battery and the fuse box in there.

As far as the throttle goes, it is set up properly although the picture does make it look incorrect. I can certainly check it another time and see if that inst triggering the TPS as fast/accurate as it should be, but I feel pretty strongly that this isnt the issue.


Do you guys think a knock sensor would cause a break up? Both are hooked up but I never tested them. I plan on hooking a CEL up next and making sure I dont have any codes(kind of dumb to do all this so far without one I know). I also have a SAFC that I will install and that should give me a TPS voltage readout that can help me see if theres something odd happening with the TPS.

[Daddio]

[QUOTE=jdesign;1617100]This is worth checking I guess. It doesn't seem like its running on 5 cylinders which is what I would assume this would do, but I will check it and report back.

Funny thing is, it didnt run on 5 cylinders...it started/idled great, fine off boost, and fine to around 4000rpm on boost, then a wierd miss.
I doubt a knock sensor would do that, my experience has been if the sensor senses knock it throws a code and drops into limp mode....

Just a thought...is the ECU a JZA70 one? If so, have you had a look at the capacitors on the circuit board?? Its a known issue the caps start to break down (chinese rubbish, unlike those used on the previous 7M's and later JZA80's which were better quality Japanese)...its a reasonably simple job to replace the caps (couple dollars worth of parts) which can cause all manner of strange things including massive over fuelling....worth a look

[jdesign]

[QUOTE=Daddio;1617105]

This is worth checking I guess. It doesn't seem like its running on 5 cylinders which is what I would assume this would do, but I will check it and report back.

Funny thing is, it didnt run on 5 cylinders...it started/idled great, fine off boost, and fine to around 4000rpm on boost, then a wierd miss.
I doubt a knock sensor would do that, my experience has been if the sensor senses knock it throws a code and drops into limp mode....

Just a thought...is the ECU a JZA70 one? If so, have you had a look at the capacitors on the circuit board?? Its a known issue the caps start to break down (chinese rubbish, unlike those used on the previous 7M's and later JZA80's which were better quality Japanese)...its a reasonably simple job to replace the caps (couple dollars worth of parts) which can cause all manner of strange things including massive over fuelling....worth a look

VERY interesting. I havent had time to check the coil pack polarities but I will tomorrow.

The ECU is in fact a JZA70 and I did take a look at the Capacitors. They are kind of hard to see, but they did seem to be weeping a tad. On a scale from 1-10, 10 being completely destroyed, I would say they look to be a 2-3.

I also swapped ECU's a while back before making a lot of other improvements and it still had the same problem. It wouldn't hurt getting my hands on another ECU again and checking though.

[Daddio]

[QUOTE=jdesign;1617141]

VERY interesting. I havent had time to check the coil pack polarities but I will tomorrow.

The ECU is in fact a JZA70 and I did take a look at the Capacitors. They are kind of hard to see, but they did seem to be weeping a tad. On a scale from 1-10, 10 being completely destroyed, I would say they look to be a 2-3.

I also swapped ECU's a while back before making a lot of other improvements and it still had the same problem. It wouldn't hurt getting my hands on another ECU again and checking though.

Aha! JZA70 ECU's are terrible for this I had mine fully refurbished, despite them looking OK (very slight swelling) they car ran fine for about 2 mins, then pig rich (to the extent of 20 litres of fuel to get the 35km home and associated clouds of smoke!) Caps are cheap and not hard to DIY (I now keep a spare rebuilt ECU, probably overkill but comforting)...I would certainly be spending the $5 for new caps, if not the $200 for a full refurb!

[jdesign]

[QUOTE=Daddio;1617142]

Aha! JZA70 ECU's are terrible for this I had mine fully refurbished, despite them looking OK (very slight swelling) they car ran fine for about 2 mins, then pig rich (to the extent of 20 litres of fuel to get the 35km home and associated clouds of smoke!) Caps are cheap and not hard to DIY (I now keep a spare rebuilt ECU, probably overkill but comforting)...I would certainly be spending the $5 for new caps, if not the $200 for a full refurb!

They are not swelling, and I dont have any fueling problems, but I know that there can be a ton of other issues related to failing caps. Do you have any suggestions to where I should buy new caps, I will probably do it myself and have an Electrical Engineer look over my should while I perform the surgery.

This is the best tutorial I have found to date:

http://www.mk3supra.org/topic/9-guid...-on-a-1jz-ecu/

[ar5boosted]

[QUOTE=jdesign;1617164]

Do you have any suggestions to where I should buy new caps]

Jaycar, element14.com.au, ebay.com.au, aliexpress.com

[Daddio]

Try the above, or RS Components, RadioShack, etc...I didnt have to source them as the refurb company did it.

I disagree slightly with the tutorial, only in so much as its quite well known that during 89/90/91 Toyota sourced cheap capacitors from China instead of quality Japanese made ones, hence so many issues. I think China has leaped forward since in terms of quality.

[jdesign]

So more items checked off the list and the problem still hasn't surfaced.

-Checked all of the coil wires and the polarities are all correct. Im getting full voltage across all of them as well.
-Added a check engine light and tested it to make sure it was working. Hooked it up and got no codes at all. Is this diagram I made correct?


-I also added a ground from the cylinder head to the chassis of the car directly to where the harness grounds are mounted.

-I also swapped ECU's which did make a difference. With the 2nd ECU, the idle is much better and much smoother. Although, taking it for a drive, it still breaks up, but feels completely different from the other ECU. It seems to cut in and out more like a fuel cut rather than a spark issue. My wide-band is reading 14.5's cruising, and under hard throttle slowly goes to 10.5ish. once it breaks up, I can see the gauge leaning out back to 12-14's.

Click the image below to see/hear a video of it breaking up so you get an idea of what it sounds like. Im sooooooooo close to just buying an ECUmater and not dealing with this anymore. I just want to enjoy the car and its been months of trouble shooting.

[Daddio]

Have you swapped ignitor with a known good yet?

[jdesign]

Have you swapped ignitor with a known good yet?

Yes. Originally I did. When I first got it running. Its worth a shot again, I will grab a spare tonight from a friend.

[jdesign]

Yes. Originally I did. When I first got it running. Its worth a shot again, I will grab a spare tonight from a friend.

My friend doesn't have a spare, I will be on the look out for one to see if I can try that. Is there any way of testing the Igniter to make sure its working properly in case I cant find a local one to test? I really dont want to spend more money on parts that will be just useless once I go standalone after I cant get this sorted.

[Daddio]

My friend doesn't have a spare, I will be on the look out for one to see if I can try that. Is there any way of testing the Igniter to make sure its working properly in case I cant find a local one to test? I really dont want to spend more money on parts that will be just useless once I go standalone after I cant get this sorted.

Sorry, I dont have any test procedure for the ignitor, other than swapping with a known good one. Pretty sure either a 1J or 2J (GTE) non vvti ignitor will be same although part number (89620-14460) is different...