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HHR doesn't rev past 4000 rpm and won't go over 40mph
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HHR doesn't rev past 4000 rpm and won't go over 40mph
I have an '09 HHR with the 2.4 l, and it sat for a week while we were on vacation. Then when my son went to get back in it to drive home it wouldn't go above 40 mph. It also won't rev past 4,000 RPMs, I'm not sure if that's a safety thing or if that's part of this issue. The only fault code I'm getting is p0420, Catalyst System Low Efficiency, but it's only in the historic fault codes. Occasionally I will get a pending p0300, Engine Misfire Detected, but I have checked all of the coil packs, new plugs and new coil boots,
as well as checked the electrical connections to the coil packs. Unfortunately I don't have a bi-directional scanner that I can check the fuel injectors one by one. One thing I noticed using my cheap little scanner is that the throttle position never reaches 100% and it maxes out at 40%. I do notice that when I step on the gas pedal when it gets up to 4,000 RPMs I can still press the gas pedal but nothing is happening for the rest of the travel.
So far we have put new VVT solenoids in because both of his were reading infinite ohms, new plugs, and new coil boots. I also checked the new spark plugs after running them for about an hour and I don't see any of them that are fouling or not getting used.
P0420 indicates a clogged catalytic converter. If it is historic it should have cleared after 100 starts. Was the cat replaced, P0420 does not fix itself? Is the CEL lit up?
So far you have wasted money throwing parts around. No need to replace VVT valves unless they are throwing a code.
I would propose an experiment; remove the downpipe from the manifold a try the engine to test the cat.
Have you removed the cam cover and looked at the timing chaon? Any slack between the sprockets is bad.
If the car is clogged you need to find out the "why" or it will happen to a new one. Persistent P0300 can do it,
The catalytic converter has never been replaced, the CEL is not lit up, it's only showing up as a historic code.
I haven't wasted any money, as I stated in my post I replaced both VVT solenoids because both of his were reading infinite homes and would not click when applied power to them. So I replaced them because yes they were throwing a code, they are not now.
I have thought about removing the down pipe and trying your experiment but haven't gotten that far yet.
I did remove the cam cover and I don't feel any slack in the timing chain any where.
Code p0300 is not showing up now and as stated it was only a intermittent code showing on my code reader as pending, but has never lit the CEL up.
You did not say that you had VVT codes. A VOM or clicking test does not tell you much as they are PWM, not on/off.
So, what made the P0420 clear? Do you keep clearing codes? What is the I/M readiness status? Did the CEL ever flash on/off? Does the CEL light momentarily at key on?
My experience with P0420 is that it will not pop up until after the EVAP test runs, that can be 40 drive cycles. Every time the codes get reset testing starts from day 0.
P0300 doesn't light the CEL until it occurs in 2 consecutive cold start cycles. It means that the condition might cause cat damage. I does not mean whatever nonsense your reader "says". It actually means that the crankshaft is not maintaining a constant speed. like what would happen if a cylinder did not fire but there is no data from the camshaft sensor to tell which cylinder.
The only codes that ever showed up and turned on the cel is the VVT code. Since clearing that code after replacement the cel has not come back on. I haven't cleared codes in probably 30 cycles. It does come on when key is first turned on.
As far as the 0420 code it has only ever appeared as a historic code that I am aware of. It was there as a historic code when I found the VVT codes. No other codes have actually lit the CEL light except the VVT one. The 0420 is historic and the 0300 only appeared a couple times as a pending code.
In order to be historic it had to once have caused the CEL. That is what historic means.
One more time what is the I/M readiness status? I bet there is at least one not ready.
So I did it suggest and removed The flex pipe and I still can't get above 40 mph or 4,000 RPMs. As soon as it gets to 4,000 RPMs it spits and sputters and coughs and if I don't let off the gas and accelerate again it'll try to die.
IM readiness shows catalyst, evap, O2 sensor, incomplete.
I am now getting a pending code of p0171, my guess, because the O2 sensors weren't getting the data they needed.
As far as the historic code p0420, I'm not arguing it's not there and not there for a reason, I'm just stating I'm not sure why it's in historic. It is possible my son checked the codes when it first started acting up and cleared them instead of telling me about it.
I didn't know if these had a rev limited or not. But if that's the case that explains why I can't get it above 4000 RPMs, but it doesn't explain why I can't go over 40 mph.
An update from my son, he drove 2 hours to get here, and on his way here he said it briefly acted up, but then went right back to normal. Then after the car sat for 10 days, he went to drive the 2 hours back home and couldn't ever get it above 40 mph. Will a catalytic converter cause it to suddenly act like this? I always thought they deteriorated over time, but could be wrong.
08-03-2023, 09:02 AM
