Hi there everyone. I am currently trying to repair my car and was hoping for some insight from you guys as to what could be the problem. It has been to 2 mechanics (including the dealer and so far $1300+ has been spent in parts and labor with no fix).
It is kind of a complicated case, but I will try to be brief.
Car: 2002 Ford Focus ZX5 Vin "3" DOHC Zetec motor with manual transmission.
Problem: Starts but wont idle and stalls seconds after starting, despite trying to give it gas. If you start it (and stall it) several, several times so that the engine warms up, sometimes it will run just fine all day until next cold start.
Replaced: MAF sensor, TPS sensor, Idle air control valve, alternator, pre-cat 02 sensor, spark plugs, spark plug wires, ignition coil (14k ago for the coil).
Exhaust leaks have been repaired. No obvious intake leak.
When it runs (and it runs very rarely), it runs mostly lean, but at times rich (based on fuel trim numbers). There doesn't seem to be any rhyme or reason.
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The following is what I would like help with, and please correct me if I make a glaring error in my analysis.
This was taken from a recent start / run for a few seconds / then stall:
https://www.flickr.com/gp/138846169@N03/ES190u
The light blue sine wave is the crankshaft signal. It is a 36-1 tooth and the missing tooth is 90 before TDC. I wrote in white numbers the degrees before and after TDC.
The yellow is my camshaft signal. It rises and then falls and then rises again. Where it first crosses from positive to negative (in the middle of the signal) should be at 22-26 degrees after top dead center from what I have researched. You can see that mine crosses at around 38 degrees (or about 12 degrees late).
The darker blue hump is a crappy pressure transducer stuck in cylinder 1 instead of the spark plug, so I can see the cylinder pressure and tell where TDC is... it was about $13 on Ebay, so the response time and quality isn't the best, but look where the spike in that hump is: at about 12 after TDC, which means my TDC is occurring 12 degrees too late.
And here is one that I cannot explain:
https://www.flickr.com/gp/138846169@N03/0tZn9EIn this you can see my camshaft signal (blue), my spark amperage (purple) with cylinder 1
presumably just before the camshaft wave, and the voltage of the #1 fuel injector (yellow). The two white vertical lines roughly encompass the powerstroke starting from TDC.
Ignoring the fact that my spark is probably occurring too early before TDC (and sometimes I have two ramps like you see in the picture, whats up with that? Multistrike?), check out where the fuel is spraying: Towards the end of the power stroke and into the exhaust stroke. I have really tried hard to see where I am messing up in my thinking, but I think it is an accurate interpretation.
I don't know, could be nothing, but the next time I get a chance, I am going to check the timing and see if I can't find anything... I don't get it though, because the timing belt was a Gates that I put on maybe 30k miles ago, with new tensioners and pulleys. And the fact that I can get it to run (sometimes) if the car warms up enough... Maybe a loose keyway? What do you think? Thank you everyone for reading this and for all your help. You make this a great community.
Jeff from Virginia