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-   -   TPS and ICV signals on OBD2? (http://www.318ti.org/forum/showthread.php?t=44873)

paul somlo 07-01-2020 07:06 PM

TPS and ICV signals on OBD2?
 
Has anyone been able to view data from the throttle position sensor and the Idle Control Valve using something like Bluedriver or OBDLink MX?

I'm having a hesitation issue that makes me suspect one of those parts, but I'd like to get some confirmation.

Paul
'96ti 259,000 mi

BRADESTAR 07-06-2020 08:05 AM

I have a simple blutooth reader and was able to see the throttle position information. Not sure about the idle control valve.

paul somlo 07-07-2020 01:57 AM

Quote:

Originally Posted by BRADESTAR (Post 391897)
I have a simple blutooth reader and was able to see the throttle position information. Not sure about the idle control valve.

After I posted, I realized that, since there's no feedback from the ICV itself, all I could possibly look at would be the commanded value, which tells me nothing about whether the ICV is working or not. The TPS, of course, the input is your foot, and the output is from the sensor, which is useful data.

I've got this hesitation going at low speeds (less than 45mph). Almost like the throttle cable disconnects, even though I've got my foot steady on the gas. It's inconsistent though - I went for about 3 months, didn't do it. Had the car out of service for a month or so to replace some seals, drove about 60 miles, after 55 miles or so, starts hesitating again. Never at highway speeds, though. Just drove back and forth to Denver this weekend, didn't do it at all. Been going on for at least two years now. Sometimes accompanied by high/erratic idle when stopped (1200 rpm).

I'd buy a bluetooth reader, but I don't know that I'd get any useful data out of it, really. Thanks for the reply Bradestar.

BRADESTAR 07-07-2020 04:19 AM

Kinda sounds like gas. Maybe the pump or filter? I find gas to be a smooth cut of power and spark to be a pretty violent cut of power.

I have a high idle at stop too. it had been around 1200 or so. When I drove it the other day it was around 2100 while stopped, even after I'd blip the throttle a little. Probably something that it is time to address at this point. ….perhaps.

Those blutooth sensors can't see a whole lot, but at least can pull codes and reset if you're on OBDII. They do give temp and some other stuff.

paul somlo 07-07-2020 04:46 AM

I was thinking pump/filter, but I have no issues at highway speeds or accelerating. I discounted ignition, because it only seems to happen at low speeds. When I had it apart last month, I did find oil in the #1 plug well, which I seem to have fixed with some RTV on the gasket. The other strange thing, was the #1 plug had a loose connection; the part that screws onto the plug where the plug wire attaches to was partly unthreaded. I'm not sure how you'd define "violent", but when it cuts, it's like I took my foot off the gas completely in third gear at say, 30 mph, which is pretty abrupt, car feels like it's bucking.

It's funny - when I get the high idle, sometimes blipping the throttle will cure it, like the days of old with automatic choke. I had codes read at Autozone over a year ago, nothing very definitive. They handed me a printout of all the parts that I should "replace" - right.

BRADESTAR 07-07-2020 07:48 AM

I equate 'bucking' with violent. Sounds like spark. If oil is in the wells that'll do it. The valve cover set is easy and includes all those gaskets. Maybe the RTV didn't hold. It isn't expensive, the kit.

I had oil in the wells and mine would run ok, just wouldn't start sometimes. The valve cover gasket kit solved that.....can't remember where I bought from though. The oil makes the spark plug boots expand and swell up. thus loosening and not making a good connection. They should just snap on. Maybe I'm misunderstanding the threaded bit.

paul somlo 07-07-2020 05:43 PM

I put about 100 miles on it after the RTV, #1 plug well was dry. I would have replaced the gasket, but there's only about 40k miles on the one that's in there.

The portion of the plug that the wire snaps onto is actually threaded onto a small stud that is molded into the ceramic of the plug. Mine was partially unthreaded.


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