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Need help please!!! ECU issue or not?

galantvr4503

Member
Joined
Dec 6, 2014
Messages
12
Location
Portland, Oregon
Recap what going on with my car. I took my car out of commision to installed suspension parts, 2G Maf, chip flash with Tuner Pro for 550cc injector. The car was a runner with 450cc injector prior to this project.

Now the car has:
550cc Evo 8 injectors
Big 16 Turbo
2G Maf 501

I'm not new to this tuning stuff, this one stump me. This what I have done:

-I have all new temp sensor installed thinking that it could be bad.
-Rewire ECT wire, it was brittle and normal for these car.
-Rewire for 2G MAF.
-2G TPS sensor wire in.
-Checked for vacuum leaks and pressure leaks.
-Replaced all throttle body seal.
-Replaced ISC motor.
-Triple check all my wiring that I modified and they all correct to ECU pinout.

Summary:
I tried to start in small increment on this project and didn't want to get crazy.
The issue i'm having is at idle and after rev. The car will die after high rev. I'm narrowing it down to ECU. The closed TPS signal is there when the ECU power up and after it started the signal is an open. The only thing that control it is the ECU. I did do all my pinout verification and wiring resistance test. They are good.

What do you guy thinks?

Thanks John
 

galantvr4503

Member
Joined
Dec 6, 2014
Messages
12
Location
Portland, Oregon
Update: I was reading through the forum and found a post in regard to ECT temp troubleshooting. Running Tunerpro logger, the feedback for ECT was @ 270F at normal operation temp. That almost a short reading. Checked the actual feedback using the voltage to temperature reference table and my laser thermal gun,signal to ECU pin is correct. There is about 100 degree of differences between actual temp and Tunerpro feedback. It's pointing to a bad ECU. Suggestion or comment?
 

thomcasey

Well-known member
Joined
Sep 24, 2014
Messages
907
Location
Indianapolis, IN
What does the ECU see when engine is cold/overnight?
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
Quoting galantvr4503:
Update: I was reading through the forum and found a post in regard to ECT temp troubleshooting. Running Tunerpro logger, the feedback for ECT was @ 270F at normal operation temp. That almost a short reading. Checked the actual feedback using the voltage to temperature reference table and my laser thermal gun,signal to ECU pin is correct. There is about 100 degree of differences between actual temp and Tunerpro feedback. It's pointing to a bad ECU. Suggestion or comment?



Welcome to the board.

It can be difficult to t-shoot a bad ECU if the problem is in the logic. That being said, the ECU in these cars tends to fail in a more spectacular fashion. I would start by pulling the ECU out and inspecting it for burned-up bits or leaking capacitors. If the ECU you are using has never had it's capacitors replaced, it's going to be well-overdue for leaks (since it seems to be not an "if", but a "when").

Check out the ECM Tuning ECU repair page to see photos of common failures.

click

Good luck!
 

galantvr4503

Member
Joined
Dec 6, 2014
Messages
12
Location
Portland, Oregon
Thanks for the reply. I checked my ECU, the CAP has been replaced. I didn't see any burn mark or any sign of corrosion. I know it common for certain resistor, caps, and ISC driver to failed on this ECU.I would do more research and test some components. That bad things about testing CAP, it must be remove to get correct reading. Any schematic drawing for these board?
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
None that I can think of, but ECM Tuning might have one they can send you. Worth asking, anyway.

Have you inspected your ISC motor off the car? I know there's a testing procedure where you can put 6v across the contacts and actually watch the stepper-motor operate. What you are describing (stall after rev'ing/ I assume it can hold an idle) sounds a lot like the ISC...
 

galantvr4503

Member
Joined
Dec 6, 2014
Messages
12
Location
Portland, Oregon
Yes I inspected the OHM reading from each pin. Removed it to see if the plunger would reset, which it did. It was reading 40 ohms. I bought a new ISC motor and it still did the same thing. I'm searching through forums to get a replacement ECU to prove my theory. I loved troubleshooting and finding resolution with any car I work on, sometimes I just want to drive the dang thing.

In the future I'm looking into the EVO 8 ECU into this car. I'm tired of the OBD 1 stuff, I do some research on it.


Thanks for the reply.

John V.
 

thomcasey

Well-known member
Joined
Sep 24, 2014
Messages
907
Location
Indianapolis, IN
I think what he is saying it to take the ISC out and apply +6v to the proper pins and watch the motor step in and out. The ISC can ohm out fine and still not work.
 

iceman69510

Turn Right Racing
Staff member
Joined
Mar 5, 2001
Messages
10,881
Location
Michigan
Quoting galantvr4503:
In the future I'm looking into the EVO 8 ECU into this car. I'm tired of the OBD 1 stuff, I do some research on it.



That's not going to change the functional hardware on the engine.
 

OldHairyBastard

Well-known member
Joined
Apr 27, 2005
Messages
4,506
Location
Lindenhurst, IL-Northern Chicagoland Area Near The
galantvr4503 do you have a lightened flywheel on the car and are you venting to the atmosphere instead of recirculating? These two things make it hard to keep the engine running at a good idle and after a high revving run or just pushing in the clutch to slow down at a light. You have to have your biss screw set perfect and you will still have an occasional stall. Now if you have 272 or high cams it's even harder to keep it running at idle and after a WOT run.
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
Great points, OHB. For my part on 264/264 cams, I fixed 95% of my post-check/fix-everything-else idle drops by changing my idle RPM's from 900 to 950. This is after checking the ISC driver chips, checking the ISC itself, adjusting the BISS, replacing the BISS washer, cleaning the TB, and doing a boost-leak test. This slight change in idle even sorted out my cold-start stall-after-15-seconds-on-the-first-crank issue.
 

galantvr4503

Member
Joined
Dec 6, 2014
Messages
12
Location
Portland, Oregon
Understand it not going to change the hardware of the engine. I took out the ISC motor to watch it retract and reset just find. I even order a new one.
 

galantvr4503

Member
Joined
Dec 6, 2014
Messages
12
Location
Portland, Oregon
My motor is pretty much stock. The car is venting to atmosphere for now. I order the tubing to recirculate the air back. Recir or not, the car will run rich if vented. My problem is the idle swing due to incorrect temp sensor and my idle switch signal is open at closed position during running condition. I tried adjusting the idle screwed, no luck.
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
Assuming the temp sensor is fine, then it sounds like either the ECU or the chip has an issue.

I'll go ahead and say it first: invest in ECMLink. You'll never have more control over your engine and the logging cannot be matched. You can order a kit from ECM Tuning and drop it in, both upgrading your ability to tune your car, as well as addressing the concern that the chip or current ECU has an issue.
 

thomcasey

Well-known member
Joined
Sep 24, 2014
Messages
907
Location
Indianapolis, IN
If you have a stock or 2gMAF and are VTA, then you will stall dropping off the gas as you lose all the metered air. As said above, invest in ECMLink, it does wonders even on a stock motor.
 

galantvr4503

Member
Joined
Dec 6, 2014
Messages
12
Location
Portland, Oregon
I'm running tuner pro and already flash the EPROM for the current setup. I'm logging it with Kalon ADX and waiting on my palm pocket logger to arrive. I just PM another member with a stock ECU and hopefully he can meet up with me to swap ECU. That the only way I see this resolve.
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
Really? Which other member in Portland? There aren't many of us!
 

galantvr4503

Member
Joined
Dec 6, 2014
Messages
12
Location
Portland, Oregon
dime2nr is from Portland. We should meet up these day, just to share the same passion about these car. I have been a long time fan of these car and the mitsubishi brand.
 

galantvr4503

Member
Joined
Dec 6, 2014
Messages
12
Location
Portland, Oregon
Really thanks for all the reply. I haven't been an active member in any forum. I missed out on the last winter storm here is Portland, this year my mission is to get this car on the road.

Thnx for help.
 

Fish

Well-known member
Joined
Nov 12, 2012
Messages
206
Location
Idaho Falls, ID
If you end up needing to check your coolant temp sensor circuit I made this post a few months back that should help you out.

Very last post
click
 

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