So its been 2 weeks now trying to diagnose a no start issue in my 2004 XB but still havent figured out and i have tried everything i can think of. First off here is what i have done and if anyone can think of anything im missing let me know:
Changed spark plugs, checked all four coil packs for spark, changed out air filter, checked for fuel to all four cylinders, changed out Camshaft sensor, changed out crankshaft sensor, checked all relay and fuses, changed out ECU. There are no trouble codes either when the key is in ON position. This happened 2 weeks ago, i turned the call on and it sounded like it mis-fired so i quickly turned it off so it never had a code thrown. Thanks for any advice as i am completely stumped.

 

go and have the master key reprogramed for your car.

 

Master key? I only have one key as i bought this car used from a dealer and my key has no buttons or anyting, it looks like a factory spare key so that may be a problem. I forgot to mention that the car is cranking and trying to start but there is obviously firing sequence timing issue.

 

This is a MT, and yes I have rechecked every connection. I have not yet looked at clutch ignition switch, so i will try that next. If it were the clutch ignition switch though would it be cranking? Because it is cranking and sounds normal just not starting. Also just thought of something i havent checked yet and that is the timing chain itself to see if it has any issues, I have neglected to check it since its a chain and not a belt so typically there are not many problems with them and i have only 60k on the car but i guess i shouldnt rule it out.

 

Thanks a bunch for taking the time to respond. Yea we went though the basics to determine fuel, air and spark and had all but not being to familiar w/coil over plug ignition systems i went ahead and relpaced sensors just to be sure. When i determined that all coils were sparking and i had fuel soaking the spark plugs everytime it was suggested that my ECU had crapped out which i assumed very unlikely but found one used that was the exact same serial number from the same year car with the same MT. But still know avail. So with air, fuel and spark im now going to the mechanical side which i probably should have done in the first place but over thunk the new coil over plug system. I did do a compression test last night and they all were very low but silly me forgot to open up the throttle all the way when testing so i have to retest. If the compression is low then i will check the timing chain to enusre it didnt slip. Thanks again for your help any and all suggestions are welcome because im at a loss.

PS: Is there a simple way to test the VVTI controller, im at work right now so its difficult to spend to much time on searching the net and the maintnence manual to find out.

 

Again thanks for the post you have been very helpful as i would never have thought to check the VTT-i system. After redoing the compression test properly this time and if it is low then i will start looking at the timing chain. But the idea of the VTT-i system being flawed sounds very plausible so if the timing chain/compression ends up not being the issue i will give up and take it to a dealer and have them inspect VTT-i first since i have pretty much done all the other diagnosing for them lol.

 

I will for sure post wheni get this figured out as this has been such a mess it may save a headache for someone later on. If it is indeed the VTT-i controller would the fix then just be to replace the oil control valve (if that is actually a replacable part) or is there something else that would need replaced/fixed?

 

Nevermind my quesion in previous reply, i found the OCV and the filter underneath that as well. I pulled both for a visual inspection and both were clean of build up or gunk. So is there some way of testing the OVC? I know the VVT-i electrical side should be fine since i replaced the ECU so if it is indeed the VVT-i system that leaves the mechanical side which would be this OVC. I just dont know how to check this piece as i really dont want to spend more money on buying a new one to find out that it as well was not the answer. Also a follow up to the timing, i checked cam position and crank position and they are right in line so that eliminates possible timing chain slippage.

 

EDIT to post i just did about 15min ago. The problem is SOLVED!!!! It was indeed the Oil Control Valve portion of the VVT-i system. I replaced the part for 107.00 from my local dealer. It didnt start right up however, i cranked it few times then removed the spark plugs to clean them since they were becoming fouled. But after doing that a couple times the OCV got everything lined back up and it fired up!! Thanks to FROGBOX for pointing me into the VVT-i direction or i would have ended up spending a lot more money. Thanks FROGBOX!!

 

More very good info, for future. Nice thread.