xtahoex

Hey all...

I am working on a 1uz swap into an old chevy. Everything is virtually done. I have a situation where my engine doesn't want to idle unless I really baby the throttle to a point where it will idle but it's rough. There is also a hesitation/miss under throttle while driving. I got the drive train from a donor vehicle that ran when I bought it. I changed the timing belt, plugs, wires, caps, rotors, coils, water pump...

Once I got the motor running I started reading different forums to figure out my issue. I think I have done everything to attack the problem. There are not any CELs at this point (drove it pretty hard today trying to throw any type of code). At this point I am ready to take it to a mechanic and that is not my style at all. Here is the list of what I have done.

Compression Test: All cylinders between 137 and 144 (I know its low)
IACV deep cleaning
TPS adjustment (didn't even alter the idle RPM, which I thought is odd) and then a new TPS (same function)
Tested my MAF (It's good)
New Injectors
Checked for Vacuum Leaks via Brake Clean (no change from motor)
Verified ignition via inductive timing light.
Verified my timing belt was aligned correctly post timing belt change
Seafoam
Cleaned fuel system (prior to changing injectors)
When I pulled the plugs tonight I noticed one of my plugs was sooty (cylinder with 137 PSI compression)
Pulled out lots of my hair...

So does anyone have any advice? The compression is somewhat concerning to me due to the fact that the number are just under factory spec. But I would still think it would run and idle. When I drove it today I went heavy on the throttle and I was able to get the transmission to kick down and it rev'd up over 5000 RPM. I can feel the power that the motor wants to give but that miss/hesitation is just killing me. Please Help!!!

Ryan

dicer

You've only told us half the story. What year car is it all from? Did the donor car have trac? Are you running all the O2 sensors? So I guess the transmission was included in the swap?
And why swap into a chevy? The chevy running gear is way better in my opinion. Way more fool proof and easier to work on.

xtahoex

[QUOTE]You've only told us half the story. What year car is it all from? Did the donor car have trac? Are you running all the O2 sensors? So I guess the transmission was included in the swap?
And why swap into a chevy? The chevy running gear is way better in my opinion. Way more fool proof and easier to work on./QUOTE]

Dicer,

It was pulled from a 92 model year, no Trac, all of the O2s are wired in. Yup transmission came from the donor car. As far as the Chevy vs Lexus motor opinion... it doesn't bother me to bastardize my truck. I've had it for 20 years and wanted to do something different with it than a SBC and a carb. I needed it to be reliable and cheap. So far I got the cheap part square away. It's the legendary Toyota reliability that I'm missing.

dicer

So does the ecu have all the new capacitors? Is the idle air control motor in good shape? Reliable? Can't beat the old stuff for that. Added complexity and electronics is not synonymous with the word reliable. Especially with all the connectors, and transducers, etc. I'd much rather be broke down in the middle of no ware with an old 55 to 59 chev car or truck than any car with electronics in it. And if the problem was a water pump, its astronomically faster to change than the one on a prized 1UZFE. And a starter? Maybe 15 minutes max.
And best of all you could push start if you had to whether it be a manual or automatic transmission cool uh?

xtahoex

Yes, I rebuilt the ECU with new caps. The IAC was opened up, cleaned, inspected, and appears to be functioning.

I didn't start this thread to discuss the merits or ponder the idea of putting a 1uz in a Chevy. It's mounted, it's wired, it just runs like ****. Any advice?

nthach

Did you replicate the factory grounding for the engine block and wiring harness? How's the ECT(coolant temp) sensor working?

xtahoex

I grounded block to frame, frame to body, body to block. I want to say that the block ground point I used was on the drivers side head. I will have to check that and check that it is a good ground. I just read on how to do that with a voltmeter.

I have not done anything with the coolant sensor. Would that throw a code of it was bad? From what I just read about the sensor it would not cause the symptoms that I am experiencing, am I wrong?

Thanks for the input.

xtahoex

Anyone else?

RA40

iTrader: (6)

My thought is to try another ECU. Possibly there is a break in the wiring harness that may be need to be traced down.

xtahoex

I still have not solved this issue but I have been working on it.

Current Status...

The car will start if I give it throttle, and if I baby the throttle down I can get it to idle at a low RPM. I have one cylinder that is fouling a spark plug with what smells like fuel (found this during compression test) To verify if it was a bad plug causing a poor spark, I bought a new plug and installed it today. Same condition... I had a neighbor over today that used to be a mechanic (years ago). We pulled the plug and wire and wanted to check for spark. I cranked the motor without a plug in that cylinder and the car idled better than it ever had (without giving it throttle). The spark was not a great spark coming from the plug according to my neighbor. I put the plug back in the head and left the wire off to see if it would again idle. It would not. It required throttle to start and run the motor. I replaced the spark plug wire on that plug. I pulled a plug and wire from a different cylinder on the other side of the motor and tried to replicate the good idle. The car started without throttle and idled. I am at a complete loss as to why this is occurring and how to solve the issue and get a good idle with all 8 cylinders.

I went through the ignition section of the FSM tonight and tested all of the components. The primary resistance on one of the coils was high. I plan on replacing it tomorrow. Besides that everything checked out within spec.

Any thoughts?

VolumeToo

Does your new setup include the fuel tank and pump from the donor vehicle?

xtahoex

No, I used the stock Chevy tank and replumbed it with a return line. I am using an external efi pump.

nthach

What kind of external pump are you running? The fuel pumps in these cars are controlled with a ECU-switched relay that supplies 6-8V or 12V to the pump depending on engine demand. a typical Bosch or Pierburg-style inline pump much like that used on older Mercedes V8s(NOT the small VW ones) do supply more than enough fuel to meet a stock 1UZ's fuel demands.

You don't need a 250+lph Walbro monster to fuel these, but a "stock-type" Airtex/Carter might not meet the requirements. I think the stock LS400 pumps are in the 160-180lph range.

xtahoex

I went through the entire ignition and fuel system. I am using a walbro knock off. I measured fuel pressure before the rail per the FSM and discovered that I am running high fuel pressure. My static pressure is 49 PSI (Should be 38-44), at idle with the regulator unplugged from vacuum I am showing 50 PSI (Should be 38-44), and after hooking vacuum back up to the regulator I am 41 PSI (should be 28-34). So I am high all around. I ordered a new FPR it has not arrived yet.

I also discovered both of my coils are showing high primary resistance. One of them was a brand new Autozone brand coil. I took it back and check 2 more of their coils in stock and they were also high resistance even for their own Autozone specs. Weird. So, I ordered a new coil and located another one in my shop that was in spec. For good measure I also ordered a new Coolant Temp Sensor.

Once everything is installed I will report back.

oldskewel

iTrader: (1)

These fuel systems have a pressure regulator in the fuel tank, as part of the fuel pump assembly. And then they also have a "pulsation damper" at the engine. So maybe you're running without a real fuel pressure regulator? Not that the pressure you're reporting seems excessively high.

I would not have worried about the coil resistance, but I know where you're coming from on just replacing them. I did that on my car when I had some running problems, and left the new ones in there, but they had nothing to do with the problem. Saved the originals for any future trouble shooting.

Sounds like a very cool project. Good luck finishing it up.

Where are you in the Tahoe area?