Hey guys.
I'm a mechanic from Australia, here in Houston.
I've got a close friends 2006 Chevy HHR 2.4L NA which I did an engine swap on.
166xxx on the chassis. The newer motor has 120xxx.
Friend stated the A/C worked great.
After swapping, the engine ran PERFECTLY when I first started it.

Then I touched the throttle.... and it stuck up at 2500rpm and doesnt want to come down.
I've been tying to have the ECM relearn the idle rpm by driving (which one GM expert technician recommended).
The rpm settles back down to normal when in R or D holding the brake, but the second I touch the throttle, she shoots back up to 2500rpm when in gear... but when I hold the brake it settles back down to correct rpm, until I again, touch the throttle.
This happens also in P or N when I touch the throttle, but the only way to get the rpm down, is to put it in gear and do what I've just mentioned.

Its driving three of us mechanics crazy as we cant get to the bottom of it.

Now, the rain did leak in and it screwed the fan resistor the first day I got the car..
I've repaired the cowling and replaced the resistor. The fan was then working fine all on fan settings, but a few weeks later, that screwed up again too.
Fan was working ok but I've also lost the A/C clutch from clicking in. Compressor loom is connected and no fault codes there.

Now...when I was test driving it, the rev's would alternate and it seemed to correlate with the fan on speed 2 or 3 suddenly coming on, then going off again.
Saying this, I mean, things seemed* to run well, when the fan worked correctly. When the fan cut out, the engine revs changed.
Surely these cant be correlating issues because ones via the ECM, the other, via the BCM.


I've checked all the wiring around the BCM. There was drops of water, but NOTHING major. I cant pull the BCM out so I just sprayed it with WD-40 from the rear.
I've pulled apart the TIPM and lubricated it all. It was free of dust.
All fuses and relays have been tested and are fine.
I know the battery jump starter pack got put on backwards (reverse polarity) prior to first starting the car with the new engine in, so I was worried about ECM damage.
This didnt seem to make a difference due to swapping the ECM.
I got another ECM and transferred the VIN over to this. No change.
We tried putting the old ECM back in. No change.
I bought a brand new throttle body.... same issue as the original with the high revs.
I tried to reset the idle via my Xtool D8- no change.
I tried to relearn the Crankshaft position sensor - but keep having issues with trying to get it to idle at the required rpm.
We removed the Viper alarm system which did help with some of the cluster issues.

What else could be going on here? This has taken MONTHS of constantly working on and Im exhausted with the time I've spent on it, which I cant charge for.....

....Help

 

During your engine swap, the fuse box was removed, that being the case it probably needs to be split to inspect for bent pins then re connected and the bolts tightened to secure both halves

https://www.chevyhhr.net/forums/how-...rmation-59520/

 

No, the fuse box was left. I only disconnected the specific loom wiring related to the engine. The transmission and everything else stayed as-is.
I took out the old, screwed 2.4L and put in another one. Like-for-like

 

By "cowl" do you mean the butyl patch under the cowl? That is where the water infiltrates.
Since you are a mechanic, I assume that you would mention a CheckEngineLight?
My guess is somehow the transmission output sensor got mucked up. It lives on the passenger side.

 

Sorry, correct. I meant the butyl patch.
I've gone through all the codes with the scan tool.
It seems to give different things at different times mainly related to BCM things (which could be from water getting into the cabin).
Yet, not much comes up with the ECM or Trans.
I'll go there tomorrow and do another scan to show what comes up.

Your trans output sensor suggestion: Hmmmm
Thanks. I'll look into this. Although no transmission codes came up...
Do you happen to have a pic of the location for that sensor?

 

The codes that you think don't mean anything are important for diagnosing; that's why they are called "On Board Diagnostic Codes".
<Diatribe deleted>

 

Precisely what year and model did the new engine come from? Same displacement?

 

"Then I touched the throttle...."
Sorry for the possibly stupid question, did you touch the throttle in the sense that you started moving the valve with your fingers?
If you really did this, you could have damaged or displaced the valve turning mechanism. It's pretty soft unfortunately.

There is one more thing... Perhaps this will give you the right idea. A few years ago I cleaned the throttle body from carbon deposits. After cleaning, the revolutions deteriorated. They explained to me that my throttle is "self-learning" and after cleaning it does not understand what happened and what engine speed is correct. It was proposed to drive 70 km and if the situation does not improve on its own - to return to the repair shop. And so it happened, after ≈ 100 km the problem was not solved and the repairmen had to reprogram something in the onboard brain. After the software was updated, everything fell into place.

 

In post #1 he states a new throttle body was installed.
the two engines are both 2.4 l


I noted you sprayed with WD40 , a water based lubricant, could cause electrical issues.

 

From the wiki (Water Displacement, formula number 40]

WD-40's main ingredients as supplied in aerosol cans, according to the US Material Safety Data Sheet information,[19] and with the CAS numbers interpreted:[20]

• 45–50% low vapor pressure aliphatic hydrocarbon (isoparaffin)
• <35% petroleum base oil (non-hazardous heavy paraffins)
• <25% aliphatic hydrocarbons (same CAS number as the first item, but flammable)
• 2–3% carbon dioxide (propellant)