1G 90 no start - oh man

[93AWDDSM]

Hey guys,

Got an issue with a 1990 TSi no start. What has happened so far, turned it over Dec. 2016 and it ran for a short period and then timing jumped and bent valves. Fast forward, the head (complete different spare) was replaced two days ago and now it's acting like it doesn't want to start.

Spark: confirmed 1-4
Fuel: confirmed
Compression: confirmed (low though... 120, basically right at service)
Mechanical timing: confirmed correct
ignition timing: can't confirm, hasn't run long enough to set 5* BTDC (also when it is running, even small adjustments of the CAS does nothing... bad?)

would that low of compression cause the car to not run? It's acting very strange it turns over many times, sometimes not even attempting to start just cranking. When it does start it's idle bounces from a very bad 500ish then revs out to 3-4K and we shut it off.

any ideas would be appreciated!

 

[92AWDHX40]

Any way to tune it. Check the no start thread here. That has a lot of information.

 

[93AWDDSM]

Going to check the Coolant temp sensor - my buddy said the plugs looked overly wet when pulled.

 

[Geeb]

Cas could be bad. Look up bad cas symptoms on youtube see if it's similar.

 

[Vegas Smith]

Could be bad temp sensor, massive boost leak and very low compression. Tuning capability?

 

[iceguru1114]

The first thing I'd advise, which you alluded to but appears you didn't actually check, is looking at the ignition timing with a proper timing light. It sounds to me like the engine is cranking, pulsing sparking, and injecting fuel, but it's probably not all happening at the correct time.

Also, if it's not even giving you the occasional firing sound, and the plugs are wet, you could be dumping in way to much fuel either during prime pulse or cranking pulse or both.

Good luck.

 

[93AWDDSM]

The first thing I'd advise, which you alluded to but appears you didn't actually check, is looking at the ignition timing with a proper timing light. It sounds to me like the engine is cranking, pulsing sparking, and injecting fuel, but it's probably not all happening at the correct time.

Also, if it's not even giving you the occasional firing sound, and the plugs are wet, you could be dumping in way to much fuel either during prime pulse or cranking pulse or both.

Good luck.

It barely wants to start and when it does get started it high revs then roughly dies. I definitely need to adjust the CAS with the timing light but I can't get it idling long enough to get the light on and adjust.

Could be bad temp sensor, massive boost leak and very low compression. Tuning capability?

we replaced the CTS today, compression is at service limit (121) but it should run at least idle. Will be doing a BLT tomorrow.

Cas could be bad. Look up bad cas symptoms on youtube see if it's similar.

Possibly this is what we have narrowed it down too. He just got a new CTS (coolant temp sensor) today. And yes the symptoms look similar.

 

[93AWDDSM]

CAS was rewired with fresh wires and completed multiple BLTs. Car starts now and is idling roughly but I'll be able to set ignition timing to 5*.