Resolved 90 specific no start

93AWDDSM · Jan 16, 2018

Hey, have a buddy’s 90 talon tsi that for some reason out of the blue is not starting.

Car is stock, no engine management/tuning besides my MMCd logger

Checked:
Spark -confirmed
(Spark plug gap correct)

Fuel -fuel pump turns on while cranking, new fuel filter, injectors spray fuel from the rail, new stock FPR

Compression -unknown? Later this evening can confirm.

Ecu -pulled it, seems fine with no noticeable leaks/Gunk.
(We don’t have a spare, so we aren’t 100% sure it’s working)

Really could use some ideas as I’ve followed the “diagnose a no start” thread but I’m running out of ideas.

It just cranks and cranks. Doesn’t even sound like it wants to fire. Can the injectors still fire if the CAS is bad?

jakk220 · Jan 16, 2018

If the CAS was bad, you would not have spark or fuel. Definitely get the compression results. Other things that I would think to check in the meantime are

1. Timing. Both mechanical and ignition (5* BTDC)
2. MAF sensor. Try unplugging it and see if anything changes.
3. Inspect intercooler and piping for any huge leaks or disconnects.

93AWDDSM · Jan 16, 2018

Mechanical timing is correct and ignition is 5*.

He was using the wrong wires for the CTS so he swapped the right ones and he said it started for a few secs and went to 3k +- few rpm and he shut it off. Once again it will not start.

No difference weather the maf is plugged in or unplugged.

I’m having him check over his intake tract throughly for any leaks/loose IC pipe.

jakk220 · Jan 16, 2018

A faulty coolant temp sensor could cause a cold no start condition. I used to have to crank my girlfriends 1G forever before it would start when hers was bad. It would eventually start though. Check the wiring to the CTS and see if they are broken or melted or anything.

Dsm panda · Jan 16, 2018

I know this may sound simple but are you getting fuel to the injectors? Also hes not low on gas is he? I know my fuel pump wouldnt supply enough if under a eighth tank. I never got low fuel light but added gas and it started fine... :banghead:

Derek232 · Jan 16, 2018

If nothing changed when you unplugged the MAF that may be your issue. On one of my cars back in the day it wouldn't start but instead it just cranked forever. Put in a new MAF and it fired right up.

jakk220 · Jan 16, 2018

Dsm panda said:
I know this may sound simple but are you getting fuel to the injectors? Also hes not low on gas is he? I know my fuel pump wouldnt supply enough if under a eighth tank. I never got low fuel light but added gas and it started fine...

Re read the post. He said that he is getting fuel to the injectors.

93AWDDSM · Jan 16, 2018

Thanks for all the ideas guys.

I have a different coolant temp sensor we’re going to swap.

Yes, he has fuel all the way. I can’t quite speak on the pressure but fuels there. New fuel filter, pulled the rail with injectors and fired into a container, confirmed all working.

I have my maf I could swap tonight while I’m there, as a possibility.

I have a question. What if it’s his ecu? He’s a 90 and I can’t swap mine into since it’s a 91+ Or can I...Would it work enough to crank, fire and start it if it was in spot of his ecu to confirm his is bad?

Derek232 · Jan 16, 2018

Did you check inside the ECU to make sure there is no burnt solder point. If I remember right theres only 2 pins on the ECU wiring you have to swap to put a 91 ECU into a 90, but I can't remember which ones they are off the top of my head. If you have a spare MAF I would put it in just to see if it changes anything, if it doesn't then you can rule out it being a MAF problem.

Dsm panda · Jan 16, 2018

I belive the only thing that wouldnt work properly after the swap of wires is the spedo but for your purpose.

e85_4g63 said:
I done cars both ways (90 ecu in a 91+ and 91+ ecu's in a 90) and I can tell you that if you don't swap the pins the cars will hardly start, if at all. The 2 pins are for the air meter. The solid green wire is the air flow sensor active reset (aka idle), while the green with with the white line on it is the idle position switch. If you don't swap the wires the ecu will not know that the car is trying to be at an idle state. Also when going with a 91+ ecu in a turbo car you'll need a tach adapter. I recommend the one that Jeff O. sells.

DSMChips.com | DSM ECU Chips Enchanced by Keydiver

Also sorry about the bad reading today. Only 2 hrs of sleep... stupid snow.

steve said:
If the car will idle with the IPS disconnected it will start with the 6 and 14 pins connected wrong but you don't get the normal functions that happen when the ECU sees the IPS close. There is no question that the car will run much better with the pins correctly set up and that why I said they should be swapped in his case.

As to will it work without swapping.

19Eclipse90 · Jan 16, 2018

93AWDDSM said:
I have a question. What if it’s his ecu? He’s a 90 and I can’t swap mine into since it’s a 91+ Or can I...Would it work enough to crank, fire and start it if it was in spot of his ecu to confirm his is bad?

As a test, direct swapping should indicate whether it is the ECU or not. Change nothing and if it was the ECU, the car should still start. A proper swap would require swapping a couple pins as has been mentioned.

motomattx · Jan 16, 2018

The plugs would be wet by this point, start with fresh ones before anymore trying anything. I have had critters build nest in the exhaust overnight causing a clog, took a few days to figure that no start out.

boostdawd · Jan 16, 2018

This helped me out a ton on a no start issue.

You must be logged in to view this image or video.

Not in order but hope it helps.

93AWDDSM · Jan 16, 2018

We got a brand new coolant temp. Car started for a few moments with the old swapped sensor and I jumped on the logger. His temp was -75* but that’s the only way it started. If the wires were in correct order it wouldn’t start. Also, when they “were” in the correct order his temp was only reading 7-9* at idle, shut it off and then it just cranks. We are replacing pins 24/20 on ecu harness with fresh wires to the CTS. I pulled the mpi fuse earlier and cranked it over a few times then plugged it back in and it hesitated but started for a moment. I’ve installed the new coolant temp sensor and just waiting on him for wiring.

I’ll post update ASAP.

Thanks guys

93AWDDSM · Jan 17, 2018

After everything checked out, it seems like it ended up being the coolant temperature sensor. He said it’s running but it’s overheating, so that’s his deal LOL

.

Resolution: New coolant temp. Sensor - new wiring to the sensor

Tried:
checked fuel pump,
Fuel filter for clog,
made sure injectors were firing,
replaced Stock FPR,
Made sure spark and compression are there,
checked CAS,
checked ECU visually

1990TSIAWDTALON · Jan 17, 2018

THANKS ......for posting back the solution. So many times, people forget to add that before they move on. Nice of you to add that at the conclusion!!! Cudo's!!!

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Resolved 90 specific no start

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jakk220

93AWDDSM

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Dsm panda

Derek232

jakk220

93AWDDSM

Derek232

Dsm panda

19Eclipse90

motomattx

boostdawd

93AWDDSM

93AWDDSM

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