skysailor

You are right...I should have a code reader. I have a number of other vehicles and it would make senses to have one. I sort of got caught up hoping for the quick fix and down the rabbit hole i have gone! :) Now have one coming in the mail sometime next week. Thanks for the advice and the nudge!

skysailor

Got my code reader. It's a Creader 529. Just used it to read the HHR and it comes up with no codes pending or permanent. Will try to get more familiar with this instrument to see if I can set it up to watch certain items while starting and during the consistent stumbling idle. Any suggestions on what to look for first and any comments regarding using this particular reader will be gratefully received.

Oldblue

Here’s the information all about how to launch and use the 529 reader

https://images-na.ssl-images-amazon....18q-RosS4S.pdf

skysailor

Thanks Oldblue. I had already downloaded that prior to purchasing the reader and studied it but have to say I am not entirely in my comfort zone regarding all the engine data and its meaning. Is there a flowchart somewhere that I can look at that shows the sequence of events for the time frame of start-up to normal idle? I have no idea what is supposed to be happening with regard to fuel trim, air pressure, O2 heating, etc. in order to get from start to idle. This problem is very repeatable and pretty much 99% of the time results in getting to normal idle within about 30 to 45 seconds. The other 1% of the time it stalls out completely. But during the problem stage it apparently does not cause a code to point me in the direction of the root issue. It looks like I can monitor the data stream for two elements at a time while the engine is running so I guess I could get it set up with power on prior to starting and then record the data stream during start/idle for some analysis. I would just like some expert advice as to which items I should look at. Oh, and also that flow chart would be very helpful...I have a distant technical (electronics) and software background so I can make some use of that info I believe.

Vinnybagodoughnuts

It might be helpful to find someone else locally with a functioning HHR to compare your readings.

skysailor

Finally got a code! A pending code generic P0300. Well that checks out as a "multiple random misfires" code with a dozen possible causes including all the things I have already checked and or replaced! Good thing this is just an annoyance and not a critical operational problem....so far.

Oldblue

That code could relate to something simple, have a read through this for causes and solutions, don’t panic and run out to buy any parts or anything, just check tge simple stuff mentioned. Cleaning the electrical connectors and applying dielectric grease can make a world of difference. Guys on my race team, and in the pits thought I was nuts during prerace assembly of our car, but those little things like never seize on the wheel studs , shock bolts anything that might need changed quickly , during a pit stop or a caution after an incident on the race track , if that got us back out a few seconds faster and better track position, it was worth that effort.
So, have a look, at those spark plugs, did you put a little dielectric grease in the coil boot to keep moisture out? And the connector at the coil, the MAF sensor, throttle body, fuel injectors? Could be as simple as that.

skysailor

Thanks Oldblue. I will be doing just that in the weeks to come. It's a very interesting problem and I agree the cause could be a very simple issue. My background in software and electronics maintenance while rusty (1967 - 2000) is keeping me focused. But I do have to embarrassingly admit to a an initial shotgun approach to the problem. I should have know better :)

Oldblue

It’s so much more fun ordering parts!! Then inspecting wires and connectors.

skysailor

Ok it's been a while but here goes. Problem on startup has been persistent but the car does not get used very often as we only bought it to use as a tow-behind for the RV. But I do use it for errands as often as possible and the other day I drove it to a doctor's appointment about 15 miles away. Had the usual rough start but the drive was uneventful. On the way home while in cruise control the car jerked a bit and the service ESC, Service Traction and Engine Power Reduced alerts came on. And yes the power was reduced to about 45 mph on the highway which put me in the way of all the traffic. So I pulled over and while stopped I plugged my code reader in and saw P0068. I turned the engine off and restarted and although the check engine light was on the engine ran fine and I was able to get home.
Google says:

What Does Code P0068 Mean?

P0068 means that the Powertrain Control Module (PCM) has detected an excessive degree of variation in the input voltage signal from the pedal position sensor (TPS) as compared with voltage input signals from the mass air flow (MAF) sensor and the manifold air pressure (MAP) sensor.

Well having already replace the MAF & MAP sensors as well as the throttle body I am thinking I have a problem with the Throttle Position Sensor on the accelerator pedal. So I remove the plug from the connector and sprayed contact cleaner on the male and female contacts and repeatedly plugged and unplugged the connector a few times. This did not solve my rough startup problem. So today, before starting the car, I unplugged the pedal position sensor connector and started the engine. It started fine, no rough start! But I did get the Service ESC & Traction plus the engine power reduced alarms. Turned engine off and reconnected pedal position sensor and got a rough start on startup. So does this definitively tell me that I need to replace the pedal position sensor?