Rough vibration at idle, Worse with A/C on

[inscarguy]

Hi all, have an issue I can't figure out and don't want to take it to the dealer. I have a '08 V8 with 117k on it. It has a vibration at idle in or out of gear. It's worse with the A/C on. With the a/c off and coming to a stop it stumbles under 5mph borderline stalling.
I have done: plugs, new vacuum lines, cleaned MAF, removed and cleaned throttle body, did a TB reset, fuel trims ok ( don't ask what they were, I don't remember), no misfires, no CEL, changed to the updated injectors.

Throttle response is poor with a/c on, worse than my '06 v8,. I punched it one day with a/c on merging on the highway and it completely fell on its face for about 3-5:seconds.

I'm used to the drive by wire sluggishness on my '06 but this is alot worse. Motor mounts seem ok as the engine seems pretty well planted.

Any ideas?

 

[waypoint]

Hi all, have an issue I can't figure out and don't want to take it to the dealer. I have a '08 V8 with 117k on ot. It has a vibration at idle in or out of gear. It's worse with the A/C on. With the a/c off and coming to a stop it stumbles under 5mph borderline stalling.
I have done: plugs, new vacuum lines, cleaned MAF, removed and cleaned throttle body, did a TB reset, fuel trims ok ( don't ask what they were, I don't remember), no misfires, no CEL, changed to the updated injectors.

What injectors did you install...Toyota part#s or are they aftermarket? Was it having this problem w/ your factory injectors?

Get more data: coolant temp, air intake temp, and LTFT data for both banks and post it:

1) At idle, operating temp
2) Cruising at part throttle
3) Accelerating hard, preferably uphill high load

And what did you use to clean the MAF?

 

[inscarguy]

What injectors did you install...Toyota part#s or are they aftermarket? Was it having this problem w/ your factory injectors?

Get more data: coolant temp, air intake temp, and LTFT data for both banks and post it:

1) At idle, operating temp
2) Cruising at part throttle
3) Accelerating hard, preferably uphill high load

And what did you use to clean the MAF?

I'll reply with the trims tomorrow and Temps. I replaced the injectors with denso 12 hole injectors vs 4 hole, calibrated for the 4.7. They are new. I had this issue with my old '08 v6 4runner and the injectors were the issue. I cleaned the MAF with CRC MAF cleaner and TB with CRC TB cleaner.

 

[MikeinNH67]

First thing I would do is monitor misfires in real time and see if there's one cylinder acting up. They don't always set a code.

BTW, didn't you just replace your exhaust with a Gibson?

 

[waypoint]

I replaced the injectors with denso 12 hole injectors vs 4 hole, calibrated for the 4.7. They are new.

Good info, and where did you buy the new injectors? Toyota dealership, a shop, eBay...? Sounds like the engine had this problem prior to injector replacement, is this the case?

edit: can you expand on "calibrated for the 4.7"? Was ECM configuration changed, and if so how?

Looking fwd to seeing scan data as I've seen temperature data really cause problems. The ECM uses both temps for fuel delivery (injector pulsewidth) calculations, so a major input error is worth ruling out.

I'm expecting to see something like significant LTFT imbalance between banks, or both running unusually high or low (my target for a stock engine and ECM tune is 0% +/- 5%, and both banks within ~2% of each other). Or reported coolant temp way out of spec (should be close to thermostat open temp e.g. 185degF). Or IAT way out of range for ambient temp condition plus an allowance for underhood heat soak.

If nothing is found there, MAF data series under same three operating conditions is the next move along with throttle position, calculated load value, and probably other stuff I'm not thinking of yet. Not just a single data point snapshot, but logging the series from idle to cruise, and cruise to acceleration under load. I've seen failing MAFs stop reporting intermittently, and you'll miss this failure mode unless you're logging it in realtime and go back to review each log line.

 

[inscarguy]

First thing I would do is monitor misfires in real time and see if there's one cylinder acting up. They don't always set a code.

BTW, didn't you just replace your exhaust with a Gibson?

I did replace with a gibson, but it was there before. I did a live data with the coils and all of them were -0-. No misfires.

 

[inscarguy]

Good info, and where did you buy the new injectors? Toyota dealership, a shop, eBay...? Sounds like the engine had this problem prior to injector replacement, is this the case?

edit: can you expand on "calibrated for the 4.7"? Was ECM configuration changed, and if so how?

Looking fwd to seeing scan data as I've seen temperature data really cause problems. The ECM uses both temps for fuel delivery (injector pulsewidth) calculations, so a major input error is worth ruling out.

I'm expecting to see something like significant LTFT imbalance between banks, or both running unusually high or low (my target for a stock engine and ECM tune is 0% +/- 5%, and both banks within ~2% of each other). Or reported coolant temp way out of spec (should be close to thermostat open temp e.g. 185degF). Or IAT way out of range for ambient temp condition plus an allowance for underhood heat soak.

If nothing is found there, MAF data series under same three operating conditions is the next move along with throttle position, calculated load value, and probably other stuff I'm not thinking of yet. Not just a single data point snapshot, but logging the series from idle to cruise, and cruise to acceleration under load. I've seen failing MAFs stop reporting intermittently, and you'll miss this failure mode unless you're logging it in realtime and go back to review each log line.

Funny you mention MAF. my stepdaughter has a camry that had driveability issues too. No codes, no CEL, multiple sensors replaced, Noone could figure it out. I had a hunch from the beginning it was the MAF as it's the first point of the system. She could never leave it with me for awhile to check it out. When i finally got my hands on it, I changed ithe MAF with a Denso one and all symptoms were gone. The rough idle, bad throttle response, high fuel consumption etc, all gone.

Maybe this has the same issue.

 

[inscarguy]

Here are the results, I could not do the drive as my rt leg is killing me today ( car accident ).

 

[waypoint]

Here are the results, I could not do the drive as my rt leg is killing me today ( car accident ).

Only thing that stands out to me in the report is the LTFTs: one bank slightly negative, one bank slightly positive. When you get cruising and high load acceleration, it will be interesting to see if the spread between LTFTs grows.