It's a good idea to fix it and use it.
So am I.
These types of problems tend to take a long time to resolve.
It confuses people because it sometimes heals once.
I would appreciate it if you could post if there is any progress.
If you keep posting and put it in the "New Posts" section, it will be more visible to people and you should be able to get a lot of advice.
In the month I've been trying to fix the P0300 code, I also developed a long hot start issue. If car is warm and I turn off for 20 minutes and restart it takes 3 seconds vs the usual <1 second to start. I'm not sure if it's related but since it's easier to reproduce problem in my driveway I figured I'd prioritize it , and it might be related to the p0300 code so I've been tackling that.
I found that yesterday and this evening I've been checking to see if crank signal or cam signal is getting to the PCM since it needs them to start.
I setup scope
channel 1 to trigger off cranking
Channel 2 cam position sensor signal
Change 3 crank position sensor signal
Channel 4 cyl 1 secondary ignition
What I'm seeing is on a long cranking start is two things
1. A 2 or 3 second delay before 1st injector pulse and or a spark issue
2. The 1st spark that normally looks real strong a quarter second later is either missing or other times it's weak looking 50-75% weaker.
Here's a trace showing the problem, it doesn't look like it's a crank sensor issue, or cam sensor. I'm going to recheck at the harness connector at pcm make sure it's not a sensor wiring issue.
FYI, light blue trace is secondary ignition on cylinder #1 for reference.
yellow trace is battery voltage relative compression waveform on crank, I actually trigger off it since I needed something that for sure will trigger starting trace since I didn't want to trigger off something that might be the problem like ignition and this way I can clearly see entire startup event, just wish I had 8 channel picoscope so I could put all startup sensor inputs in one trace.
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Here's what a normal start looks like, took about 3/4 of second to start
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They're aftermarket sensors so I'm suspicious of them but they look fine so far, and they correlate properly, so not a timing issue.
Next on the list to figure out why there's a delay w both injector and spark and weak 1st sparks and also jumping up and down burn line on the spark while running when looking at secondary ignition is
PCM's grounds, they look rusty so I'm going to ckean them. But doubt that's it as it runs fine expect the dowhill misfires. Maybe the pcm Grounds are bad and giving the injector and coil drivers that are ground switching a hard time?
I need to test also all the sensors the pcm inputs for startup mode. Which are as per 2006 service manual, can't find 2007 factory service manual and that uses jtec pcm but hopefully the inputs are pretty much the same.
1. Battery voltage which I've checked, but not at the pcm yet.
2. Intake air temperature
3. MAP sensor, I've checked it and looks to function properly but need to test at pcm it's getting good signal, live data shows its acting properly
4. Crank, which I've tested
5. Cam which seems to test good
6. ECT Engine coolant temperature, which always looks right in the scan tool. But I'll test to confirm directly at pcm
7. Throttle position sensor, never seen it reading wrong but I'll test it fully
8. ? Hopefully I'm not missing anything as that is all the service manual references.
I'm starting to lean towards a bad PCM at this point but am going to double check all the pcm inputs and outputs of course first before I condemn the PCM as bad. Need to make sure its not bad ground or wiring or eketrical noise from alternator etc first
I suspect the PCM as
1. I have unexplained downhill misfires, the only thing i can think of is its not entering deceleration mode like it should which is causing the misfires or the strange ignition problems are causing it and the idling high vaccum downhill condition is bringing out the ignition issue
2. It doesn't go consistently into deceleration mode unless overdrive is off
3. Now I see it delaying switching on the injectors abd coils for no reason, and the spark is missing or weak on the first spark, bad drivers etc?
4. The secondary ignition burn line bouncing up and down 10kv every few seconds makes me think might also be coming from bad coil drivers in the pcm. But I'm going to clean up the rusty looking pcm grounds G100 and G110 now and see if that fixes anything. If that doesn't work I'll check everything coming in out the pcm and wiring and splices and connectors to see if anything is bad.
Need to check for AC ripple ftom alternator or other noise too with scope as my cheap Autel scanner reported alternator ripple fail, but it's a new denso alternator and the oem which was working but old and aftermarket one I returned I tested all reported ripple test failure, so probably just the scan tool error.
