90 SC start up.

So I have been reading a bit about similar problems but haven't really found an answer, plus I have a few more symptoms.

Now "sometimes" when I fire up the car after it has sat over night, it's hard to start and has a slight knock for about 30s to min. Doesn't really sound like a rod knock to me or in the top end/blower.. (its hard to find out considering limited time though) When it does this, it idles rough and somewhat stalls if you touch the gas and let off. (increase revs to 1200 normally) Once it warms after 30s to min, it quickly stops, runs and starts perfectly & no knocks when driving or accelerating. What confuses me is that it only does it once in a while, not every cold start. also sometimes, it will start, stall and then have a hard time starting when warm without a knock, but then will not do it for a week.

Wondering if it could be a pre-ign knock from bad plugs (haven't had a chance to rip the motor apart to check them) a sensor or some sort or? Worst case I guess a rod knock......



Haven't had too much experience with electronically controlled motors, Only have really built and worked on carbed, other than a 5L truck with SD, and a 7.3. So not to sure about all sensors and crap on these?..

Any input would be greatly appreciated!


**Btw, Motors has 128xxx KMS. and has been dealer serviced since new.. found the receipts.

It sounds like the car is retarding timing from bad info from a sensor. The ect (engine coolant temperature) sensor could cause a lean/rich condition. The cam sensor is a common sensor problem. They dont have to fail to produce issues. If it hasn't been replaced, it probly should be anyway. I dont believe the O2 sensors are a factor in intial start-up but i might be wrong. Any codes?

Try pulling the codes....

You might have a bad sensor somewhere....

Soo, over the past while, I have been running the codes, nothing as of yet....

Now that the weathers warmer though, its rough idle has pretty well diminished. But the odd knock is still there.....

has developed another weird problem though, seems to have less power opp-on acceleration sometimes, then sometimes its fine... Sometimes hard to start, sometimes really easy... Thinking it may be the warm weather?.. ahh...

Starting to sound like a rod knock a bit though. It hadn't done it for 4 days, then today after work (had been sitting in the sun all day) it knocked like a bastard for 20 sec then decreased to nothing in about 5.. I managed to get out and listen and it was in the lower end. not the valve-train or blower... dident sound like a piston or wrist pin this time though.

Going todo another oil change this weekend, and put on a mech oil gauge to check the pressure (stock gauge moves all over the place)

Any recommendations for oil, I was running a good quality 10-30 and some Lucas.