1JZ engine stalling problem

Hey guys.

I have an E36 with a 1JZ swap and recently I've been having a problem with the car stalling. 

When the car is cold it runs perfectly fine, once its warmed up to operation temp, the idle starts acting up, misfiring, acceleration lags and it stalls. It doesn't switch back on until its cold again.

New things are:

Fuel pump

MAF sensor

MAP sensor

Spark Plugs

Fuel Pressure Regulator

Also I have tested the resistance on the fuel injectors and these are the results:

1 14.7 

2 14.7

3 13.9

4 15.7

5 14.3

6 13.8

Thanks

What kind of ECU is this car using?

Who performed the electrical work on the engine swap, and how badly hacked is the wiring?

What you are describing sounds more like a wiring problem than a failed component. You certainly could have something like a bad coolant temperature sensor, but you're dealing with a cross-bred swapped engine here, and wiring sometimes takes a beating. You could have something as simple as a circuit that goes open (loses continuity) when the temperature gets high enough.

Try to verify the integrity of all the wires and terminals on any circuit that reports temperature to the ECU. Also check the values reported by the coolant temp sensor at various temperatures and make sure they are in range. You might even find a cold solder joint inside the ECU itself.

So, it sounds like when the car is in open loop, it is running fine.  In closed loop, something isn't happy.

I'd be looking at coolant temp sensor and o2 sensor.  I get that a lot of cars will "ignore" the o2 sensor if it isn't operating properly.  However, I have had very similar symptoms that ended up being the o2 sensor.

If it's running a stock type ecu, can you pull codes?

In reply to DarkMonohue :

The car is running stock ECU. Wiring harness is plug & play bought from a professional wiring company and it's basically brand new.

In reply to wvumtnbkr :

I did perform a scan but there's no error codes.

Jvella36 said:

In reply to DarkMonohue :

The car is running stock ECU. Wiring harness is plug & play bought from a professional wiring company and it's basically brand new.

I see.  All the same, even "professionals" aren't perfect - often they're not even professional.  And sometimes a "company" is Kevin in his basement on the weekends.  Mistakes happen.  It's probably worth testing a few relevant circuits regardless of how new it is.

Since you have a stock ECU, can you log into it with a reader and watch some values as the car warms up?  If the bad behavior correlates to a sudden change in values on one sensor or another, you'll at least have somewhere to start diagnosing.

wvumtnbkr said:

So, it sounds like when the car is in open loop, it is running fine.  In closed loop, something isn't happy.

I'd be looking at coolant temp sensor and o2 sensor.  I get that a lot of cars will "ignore" the o2 sensor if it isn't operating properly.  However, I have had very similar symptoms that ended up being the o2 sensor.

If it's running a stock type ecu, can you pull codes?

If the oxygen sensor is unplugged, the computer SHOULD have a built in .450v bias voltage on the input to generate a fake signal.  It won't do any fuel trimming but it also won't slam the fuel full rich or lean, either.

Jvella36 said:

In reply to DarkMonohue :

The car is running stock ECU. Wiring harness is plug & play bought from a professional wiring company and it's basically brand new.

I've bought mispinned harnesses from a dealership, new doesn't mean good, it just means new.

Do you have an electric fan?  It almost sounds like the issue starts when the computer tries to engage it.  Like something is miswired and turning the fan on is bleeding voltage to a ground somewhere.  (All of the harness grounds are properly attached, right?  No loose fasteners to hold things in place until you cinch it down for good, a step often missed?)

I don't know how much of your car is BMW and how much is Toyota, but BMW loves to use relays with two of the terminals switched in position, in certain places like the air pump relay.  85 and 86 are next to each other not across from each other.  Those will cause all manner of weird issues if you put a "normal" relay in or vice versa.

Or if it has an evaporative emissions system, a disconnected vapor line could cause that.  A lot of strategies don't start to engage the purge solenoid until the engine is fully warmed up.  Then the purge solenoid represents a major vacuum leak instead of pulling fuel vapors from the tank.

I had a car with a weird drivability problem when warmed up that was caused by a loose airbox lid.  MAFs only sample a small portion of the airflow and the geometry leading up to the sensor is critical. When the radiator fan kicked on, it blew air into the airbox, so the MAF would read incorrectly...

In reply to DarkMonohue :

I could go to live data but what should I be looking for? This all started after my electronic throttle body stopped working and I changed it to cable throttle only.

In reply to Pete. (l33t FS) :

I have 2 electric fans and they are always on with ignition for now because without them it overheats.

I did have a vapor line going from the fuel tank into the previous engine but now its just hanging there.

Jvella36 said:

In reply to DarkMonohue :

This all started after my electronic throttle body stopped working and I changed it to cable throttle only.

I'm not sure how that is even possible to do.  Anything with drive by wire uses the throttle position as an integral part of the airflow calculation strategy.  If you removed that, no wonder it doesn't run right.

In reply to Pete. (l33t FS) :

With the electronic throttle attached I got an error code P1128 "throttle control motor lock malfunction". The problem was is when I press on the throttle nothing happens and the engine runs very bad on idle. I tested the electric motor in the throttle body and it works fine with direct power and I also changed the TPS sensor and engine ran fine on idle but still had the problem with the throttle, I hear the motor running and as soon as I press on the gas pedal the motor stops working. Then I did a "electronic throttle delete" bracket and the throttle worked and the engine ran fine but only when cold, as soon as the temp goes up the engine stalls.

Jvella36 said:

In reply to Pete. (l33t FS) :

With the electronic throttle attached I got an error code P1128 "throttle control motor lock malfunction". The problem was is when I press on the throttle nothing happens and the engine runs very bad on idle. I tested the electric motor in the throttle body and it works fine with direct power and I also changed the TPS sensor and engine ran fine on idle but still had the problem with the throttle, I hear the motor running and as soon as I press on the gas pedal the motor stops working. Then I did a "electronic throttle delete" bracket and the throttle worked and the engine ran fine but only when cold, as soon as the temp goes up the engine stalls.

So you have no IAC control and don't know why the car won't hot idle?

An approach that has always served me well: fix the problems you know you have.

Another that is equally important: fix what is broken before you modify.

You installed a cable throttle in place of the electronic throttle that the ECU expects. Instead of making an end run around a broken system, go back and fix the broken system. Figure out why the e-throttle wasn't working, and make it work.

You have a disconnected vacuum line on the fuel system. Maybe that's a factor in this behavior, maybe it's not, but it's not right. Fix that.

You have fired the parts cannon at this thing a number of times. That's not cheap and it hasn't solved the problem. Maybe it's time to try a more deliberate, more scientific approach. 

In reply to RacetruckRon :

I thought the TPS controlled that, guess not.

In reply to DarkMonohue :

I get what you're trying to say but I'm trying to find the cheapest solution instead of having to go with an aftermarket ECU to eliminate the electronic throttle body all together. If I knew what the fix was I would fix it. Could it be maybe that the actuator inside of the throttle body is acting up? As I mentioned before I have tested it outside of the throttle body with direct 12v on it and it works great, even the clutch of it works.

Jvella36 said:

In reply to RacetruckRon :

I thought the TPS controlled that, guess not.

It does and it doesn't. It does that there is a translation from pedal position to throttle position. It doesn't because it's not likely a direct pedal to throttle position, far more likely to be pedal to torque demand to air flow desired to throttle position based on conditions. 
 

And the system has safeties built in- if you get too much air, it will shut down. Or at least stop control to just idle. So if you are getting output greater than desired or expected, it will stop reacting. A leak will do that. 
  
Also, an ETC ECU won't run w/o the ETC system. Just not designed to. So either fix the ETC issue or get a different ECU set up. 

Jvella36 said:

In reply to DarkMonohue :

I get what you're trying to say but I'm trying to find the cheapest solution instead of having to go with an aftermarket ECU to eliminate the electronic throttle body all together. If I knew what the fix was I would fix it. Could it be maybe that the actuator inside of the throttle body is acting up? As I mentioned before I have tested it outside of the throttle body with direct 12v on it and it works great, even the clutch of it works.

Okay, so let's break this down a little bit.

The cheapest solution is typically to diagnose and repair what you have rather than modifying it.

None of us know what the fix is, either - we don't have the car in front of us. We are happy to contribute what we can, but ultimately, either you pay someone to diagnose the car properly or you diagnose it properly yourself. And that is a skill and mindset that is particularly hard to teach over the internet.

Anything is possible, but given what you have said, I would do three things:

1. Perform every bench test you can on the throttle body assembly and pedal. Compare both to known good spares, if possible.

2. With the stock electronic throttle body and pedal fully installed (no shortcuts, no assumptions!), watch the values of every part of them with an OBD reader. Make sure that they report as they should to the ECU and that the ECU opens and closes the throttle as it should.

3. If any part of the above fails, verify continuity of every wire and terminal between the throttle body and the ECU. Find out which wires the ECU reads sensor values from and which ones it sends commands to the throttle body through, and make sure every one of them is perfect.

With typical tools and diagnostic equipment, this is a zero dollar exercise. 

Let us know what you find!

In reply to alfadriver :

OK thanks, I have a question sorry if it's stupid but you said that an ETC ECU won't run without the ETC throttle body system but what if I eliminate the ETC throttle body and make it manually with just the cable and install a universal IACV, would it work like that? Because I'm guessing that part of the ETC performs as an IACV as well.

In reply to DarkMonohue :

Thank you for the detailed reply. OK so I will test it with live data and look up what the values should be and go on from there. Something still tells me that the actuator is the problem.

Jvella36 said:

In reply to alfadriver :

OK thanks, I have a question sorry if it's stupid but you said that an ETC ECU won't run without the ETC throttle body system but what if I eliminate the ETC throttle body and make it manually with just the cable and install a universal IACV, would it work like that? Because I'm guessing that part of the ETC performs as an IACV as well.

The engine computer will have to have the outputs and control strategy for that.

Part of the beauty of drive by wire is that they can eliminate all that.

Jvella36 said:

In reply to alfadriver :

OK thanks, I have a question sorry if it's stupid but you said that an ETC ECU won't run without the ETC throttle body system but what if I eliminate the ETC throttle body and make it manually with just the cable and install a universal IACV, would it work like that? Because I'm guessing that part of the ETC performs as an IACV as well.

On top of the lack of drivers that Pete posted about, all of the safety code written for the ETC system will fire off and prevent it from running as you are experiencing. Some of what you are saying is happening I have patents on from 1994 or so. 

Hmm OK so the only solution is to find out the problem with the ETC and fix it. Thank you