Good morning,

I have noticed something over the past few days and was wondering if anyone experienced something similar. (And if possible how to fix it). I'm leaning towards a bad map sensor but am hesitant to pay the ridiculous price for the part. I don't have the zip tie version either.

Say you are at the a stoplight and the car in front of you moves. You begin to let off of the clutch and creep forward but the car in front of you stops. You push in the clutch again to stop your movement. This is the point that the car drops below 1k rpm for a brief moment making it difficult/jerky to get back into first gear if you have to start again.

Another reason leading me to think my map sensor is bad is that there are many times the car struggles in lower gears while the rpms are low. It is nearly impossible to creep along in 1st gear without severe bucking. Likewise, coming to a stop sign in first gear while traveling around 10-12 mph, if you let off the throttle, its as if I slammed on the brakes... (I've read all the forums and understand that it can be the nature of the car, etc.) However, I am occasionally able to successfully creep above 4mph in first gear or let go of the throttle and glide along smoothly which leads me to believe a specific part is causing the issue at random times.

Any thoughts?

Thanks!

 

My first step would be to free up (NOT clean) the rotary shaft in the IAC valve.

 

If there a DIY or walkthrough for this?

It should also be noted that I have tried / done the following maintenance normally tied with this topic.

Valve adjustment
Spark Plugs
ECU reset

 

Test your battery, you'd be surprised how often a weak battery can give engine performance problems. You could have a bad battery that reads 12.6v surface charge, but once you put a load the voltage goes below 9v.

 

I just noticed I get very intermittent/occasional slight "bucking" and bogging. Though, yours sounds more extreme/worse..as mine doesn't go below 1k or change idle that much, mine isn't difficult to get back on it while in 1st and I can still "creep" smoothly/easily 95% of the time.

Bogging only happens to me like 5% of the time from 1st gear - only when going very slow (1-3 mph) and only from after I have been sitting at idle for a while. Like after a long wait at a drive-thru fast-food joint and Not with typical shorter waits like stop and go traffic (though I did notice I get it a few times while the traffic was really bad, long wait and bumper-to-bumper).


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This is just about the opposite. The S2k performs without issues about 5% of the time, and has the issues mentioned above about 95% of the time

 

IACV sounds like the culprit. Time to search for the DIY and see if it fixes my prob.

 

Cleaned my IACV and shaft just now. It was easy.

First, I did the zip-tie mod on the MAP. Like always, D100L brushed on male pins and D5 spray in the female pins. And, also, “reseated” plug 5-10x (keep unplugging and plugging back in), a neat trick done in the music studio world, and cleans/burnishes/etc any corrosion/dirt on the pins.



Now, cleaning the IACV. I didn’t have any carb/tb-cleaner around, so I just used D5 spray, as it is a good cleaner and also kills corrosion and leaves a super light film of lubrication/protection. Also, imo, I think carb cleaner would be much too strong on the bearing grease and could also possibly damage any motors/electronics.

The D5 actually worked better than expected. It’s much milder than carb cleaner; but, it still cut through the carbon build-up easily and quickly. I took my time and cleaned it with a bunch of Q-tips.

Since I didn’t have a 5-point torx bit, I just left the “plastic/motor-half” on, and simply worked and “bounce spin/rotate” the shaft, back & forth, with a Q-tip’s end (with the cotton removed for more grip). I think the shaft’s bounciness & springiness, is from the motor… so it won’t spin 360º freely like when the motor is completely removed..but, you can still tell when it’s cleaned/smooth or not anyways with the motor still in place by bounce-spinning the shaft slightly. I cleaned the shaft well too. After all squeaky cleaned, I added a few drops of D100L on each shaft’s end close to bearings, then worked/spun the shaft a couple times more to work in the lube (D100L also has a very light lube in it (more pronounced than D5 though..but still very very light)…along with corrosion dissolvers and protection). Assembled it back together and of course, once again, used DeoxIt on the IACV plug for good measure.

I’ll chime back in, in a couple days or a week; and, report if I get any intermittent/occasional bogging still or if it has completely cured it.


Before:



After:

 

Thanks, for the post and photos. I love Deoxit, too. I've revived many a tube amp & electronics bits in guitars with it.

FYI.. D100 = 100% cleaner/lubricant. D5 = 5% with volatile solvent. But, you prolly already knew this. For hotter areas, I like GN5 and G100. Rated to +250ºC (~480ºF).

 

I was going to use brake cleaner for the IACV, do you recommend picking up D100 instead?

Wasn't really sure what to use on the map sensor.

Look forward to hearing your results.

Will be doing both very soon as well.