Cleaning throttle bodies
 

Have any of you guys cleaned your throttle bodies? I noticed on the g37 forum people were cleaning their throttle bodies and experiencing real good results with engine idling. I'm thinking about cleaning mine out since I used to do it on all my other cars previously and did notice positive results.

here is link to the DIY

DIY Clean your Throttle Bodies - MyG37

anyone?

im thinking about doing this, may give it a go this weekend.

I will clean mine out on Friday and report back if anyone is interested.

I wouldn't mind hearing how it goes, how dirty they are, etc. Report back!

Just curious but couldn't you just clean them without having to take them out?

Thats how I've done it on other cars

I will snap some pics and posted them up with my mileage.

Yea thats how i did it too with my previous cars but i think because the intake manifold on the Z is plastic, the throttle body spray might mess it up. Just an idea not sure though.

Just cleaned the throttle bodies out at 19,000 miles and you can see there was a lot of gunk and dirt on them. The backside was dirtier and took some scrubbing to get clean. There was also dirt particles in the intake manifold and I wiped all that clean with just a dry microfiber. I posted a pic of the microfiber towel I used so you guys can get a better idea of all the dirt that came out of them. The backside of the microfiber has an equal amount of grime too. I did notice that car idles smoother and the revs don't bounce as much when I come to a stop.

Hate to bump a thread that's a year old, but I can't find an answer as to whether its ok to take the TB's off the car when cleaning them or not. A lot of the info I can find is from the G35/37 group and some of them have issues with the idle after messing with the TB's.

For those of you who took the throttle bodies completely off the car to clean them (best way to do so imo) were there any issues afterwards?

I haven't done it but, as long as you don't mess up the electrical parts, I don't see how it could cause a problem. You will have to recalibrate the ECU/TBs but that appears to be a straightforward process. YMMV
I'm guessing that those with problems either did something to the electrical parts or their TBs were dirty enough that the engine had to do some re-learning after cleaning.

I'm with you on cleaning with the TBs removed. If they are dirty enough to need cleaning there is a risk of moving dirt into the manifold and engine. If I were cleaning them proactively (eg, every thousand miles), I would probably do it with the TBs installed.

How exactly do you recalibrate the ecu/TBs?

Cleaning them is good maintenance. You can clean them while they're on the car, you just won't get the inside/rear bit quite as clean as you would off the car. Running a catch can helps with reducing the fouling on the back side as well. I've had mine off several times (and more than that). Removing and reinstalling them correctly doesn't hurt anything.

There's some basic "recalibration" stuff in the SM. Mostly you do these things after resetting the ECU, but it can't hurt after making intake/exhaust changes or cleaning out the TBs and cleaning the MAFs with MAF cleaner. It's all documented in Service Manual, section EC, around pages 18-20. Accel Pedal Release Position Learning, then Throttle Valve Closed Position Learning, and then Idle Air Volume Learning. If you use OBD-II stuff for a codescanner or Torque, etc, be sure to disconnect the OBD-II plug before you do these procedures or it will block them from working.

good info. Thanks!

I cleaned my tbs off the manifold when I installed the m370. Had no issues after.

You took them completely off the car?

He had to, yes. The M370 doesn't come with new throttle bodies. You take them off the old manifold and put them on the new. I went back and forth like 4 times :)

Has anyone deleted the hose on the intake tube? How dirty does that hose get vs the hose going from the PCV to the manifold?

You mean the baffled hoses that go from the valve covers to the intake tubes just a bit before the throttle bodies? Those are the fresh-air breathers for the crank-case, you need them to exist in some form or other.

So is everyone in agreement that the relearn has to be done after cleaning these?

I doubt it *needs* to be done. The air volume and flow rate is only being changed by a tiny percentage by cleaning them. It doesn't hurt, though.

It needs to be done if you disconnected the wires that are connected to it.

Did this today. Car has 20k miles on it and the throttle bodies were filthy. Did the resets and everything seems to be ok.

Really. How dirty is the hose going to the intake tubes? I take you don't have a catch can.

No catch cans. The tubes going from the intakes weren't dirty at all.

Hmm. So those tubes must suck since theyre attached to the manifold in a away but so are the TB. Surprised blow by backs up that much to dirty the TB. If you get a CC you won't have to deal with that anymore.

The PCV tubes that go from the head covers to the intake tubes (just in front of the TBs) are fresh air breathers that normally flow into the crankcase, not out into the intake tract. There can be odd reverse pressure conditions and/or backfires through them, but they also have some baffling to reduce that. Most of the fouling comes straight up out of the intake manifold itself.

Well they cant be pcv tubes since those are the hoses attached to the pcv going to the manifold. I at least wouldn't call them that. Anywho how would they flow into the crank case when the hose is attached to the intake tube? The intake tube is a giant vacuum cleaner sucking air out of those hoses. The intake sucks, it doesn't blow. Only way to over come the intakes vacuum is to have those lines going to the manifold which they do through all the hose work, valve covers, PCV etc. The manifold sucks air through the crank through all those lines. It's just more powerful than the TB's suction.

Hmmm I'd have to doubt that a little. Blow by coming up from the piston rings, out the valves, and into the manifold seems a little far fetched with a system that brings air in, not out. Since I've seen so much oil in the PCV hoses I'm going to say most of the fouling comes from them, not straight up and out the manifold.

They are, in fact, PCV-related. The PCV system has two lines (per side of the engine in our case). There's a vacuum line that goes from the intake manifold to the crankcase, which puts negative pressure on the crankcase and sucks out crankcase fumes via engine vacuum. That's the one you typically put a catch can on to get most of the nasty stuff. Then there's another line which is fresh air delivery to replace what that line sucks out. It's the fatter, baffled stock hose that attaches to the side of the main air intake tube.

Right. Gotcha. I'm interest to see what my AOS looks like in about 600 miles. Fingers crossed its low with my break in style. When I do my inlet tubes we'll see how clean the TB's look.

I personally haven't manually done the idle air volume procedure, but my techs have difficulty running the program via CONSULT.

The first attempt couldn't be done because coolant temps were too high. The second attempt couldn't be done because CONSULT would complain the ECU wasn't responding. The engine would idle up and down, values could be read, but for some reason it would output this error message.

I've always done it manually since I don't have Consult, which is a crazy procedure involving very specific timing of presses on the gas pedal and whatnot (it's documented in a time-series chart in the manual). Usually I can get it right within 2-3 tries and it works. However, one time I had a hell of a time with it. Did it over and over and over and it would never "take", like I was screwing up the procedure. It turned out the problem was I still had an OBD-II unit plugged in under the dash (I almost always do for data monitoring/logging). As soon as I unplugged from the OBD-II port the procedure worked on the first try. I'm not sure what's up with that, but my assumption was that the ECU's thinking goes something like "If something's plugged into the OBD-II port and interfacing with us, they're probably using Consult so don't worry about listening for the manual procedures?" Or it could just be a bug, who knows.

The techs didn't use the manual sequence. With CONSULT, you can call up the program (as well as other diagnostics) with a click of a button. Not sure why it's such a pain since I'm sure it had to be done at some point after getting the turbos installed.

When I change my NGK nickel sparkplugs out @ 30k miles, the TBs have to be removed, so that is when I clean them. As said previously in post 30, IF you dump your side valve cover crankcase breathers, not the PCV lines, to atmosphere (like me) or into a catch can the TBs won't become as contaminated w/carbon from blow-by. I would buy new PCVs (11810-EY00A) and PCV insulators (11812-6N200) at 90k miles on the OD.

Just to share my results, My Z was having a bad case of engine idle and some ping on low RPM's. I found a good deal on a M370 Manifold and decided to install it this last weekend. I bought MAF Cleaner for the intake sensors and when i swapped the M370 i cleaned the throttle bodies.. Man what a diference, my car is idling perfect. It feels more responsive.. can't wait to get a tune. Bottom line is that i reccomend everyone with 25k+ miles to clean the throttle bodies! I did the calibration process just in case.

There is some excellent info in this thread. Thanks guys :tiphat: I think this will be my next maintenance project. It will give also me a chance to deep clean my intake filters with some Simple Green solution :tup: I'll be sure to post my experience as soon as its done. I am hoping it helps my idle, which seems a bit "off" lately.

btw, KeVoH, it is unlikely that cleaning the TBs will make your car more responsive. The intake manifold you installed is the reason it feels that way. You should feel it pretty good in the mid range and with a tune it should improve across the board.

I agree! the responsiveness is thanks to the M370, but the idle issue went away! that's where TB cleaning came in handy :) cheers!

Reviving an old one.

Had a check engine light come on and idle issues. I took it to dealer and they told me that there was a bulletin about reprogramming the ecu, something about how my car was running rich, then lean then rich then lean and it was adding greater carbon build up on the TB. The reprogramming was covered under warranty, but the cleaning was going to cost $180.00. UMMM ILL DO THAT MYSLEF.

Anyway they told me that cleaning the throttle bodies should be done every 20k to 30K miles and should become part of my regular maintenance. Although it is not on the list of maintenance, it should be.

Will get my car back tonight and i will clean them myself tonight. They told me the check engine light will be cleared but because of the erratic idling it will pop back up till they are cleaned and working properly.

Will write back when I am done cleaning and take it for a spin.

were you guys able to clean the tb without unplugging the harness?
im thinking that if you dont unplug it, no need to do any reset sequence... :confused: