TPS question.

[HarrisonDawgs]

Been lurking here often for ideas and help. Thanks for that! New to me VZ 200 TLRD (2005 HPDI). Was running like crap, water in tank, bad fuel, etc. Drained and cleaned tank, replaced 13 filters (sep/micron/vst/pump and injector baskets, etc). Runs great but has high idle issue. Each "fix" seemed to increase the idle about 100rpms. Replaced both diaphragm fuel pumps as well. Cleaned throttle body intakes and all appear to naked eye to be synched with each other and close fully at Neutral. Metered TPS (invasive clips) and set to .52 v with idle screw up and off base. Set idle screw slowly to get .61v. Now my problem is that anytime I advance throttle (unlinked) the TPS will not read below .7 on return unless I physically turn (by hand) spring side of top shaft back to closed position. I have cleaned and lubed as much as I can see necessary without actual disassembly of throttle body. I realize I may be premature here as I have not had a chance to test motor but TPS was basically in this range BEFORE I attempted an adjustment and idle was 1200 to 1400. I plan to change thermostats. Have inspected slide and Neutral switch and they appear to be clean, unobstructed and working properly. Motor behaves the same even when I am sure it is up to temp. Wondering if I am missing something here? Also, just how critical is the TPS signal to ECM for proper idle? Thanks!

[HarrisonDawgs]

Also wondering if I should remove the mounting plate for TPS and completely remove TPS to inspect the potentiometer side of it for dirt/sludge/etc possibly hindering it from a full return to base position. Anyone ever seen this or think it's a possibility?

[HarrisonDawgs]

Wow. Anybody with any ideas? I saw a post way back where Rod said sensor (fault?) could cause high idle condition. Any idea which to chase down? Don't think this model has o2 sensor...correct me if I'm wrong. Considering buying the YDIS online (v1.33). Is this recommended by you guys or is it a waste of $? Hope to run it tomorrow but I've got a feeling the high idle will persist. Thanks all.

[TownsendsFJR1300]

The YDS is well worth the $ and isn't terribly expensive (way cheaper than a visit to the shop).

As you noted, a high idle is often a result of a code popped which may show up in the YDS.

I'm not positive re your TPS, but that high an idle doesn't sound like a TPS issue..


Someone else will chime in..



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[HarrisonDawgs]

Towns, thanks for that input. Will go ahead and order YDS as I own 2 stubborn yammys now. My thoughts exactly on TPS as well. Just don't see .7v at rest raising the idle to 1200 range but I have zero experience with voltage/vs rpm values. I assume there is an idle control valve or similar and I plan to educate myself some more since I don't even know where it is located. Thanks again brother!

[HarrisonDawgs]

Update. Cleaned all moving parts of throttle body well today. Re-checked voltage at TPS. Was still about 0.7v. After 30 minutes of massaging the set screw in between working the butterflies back and forth I got it to settle about .64v. Pulled thermostats afterward. Obvious problem on starboard stat - stuck wide open. Port stat looked horrible but worked as supposed to on stove top. Cleaned them up good, force closed the open one and re-installed (have no new ones). Launched boat. Ran perfect for 4 or 5 short runs. Idle at 500-600 in gear, 600-700 out of gear. On last run I opened her up to 5400 rpm for a couple of minutes (52mph). At dock ready to trailer it started the high rpm again. This time 1000-1100 range. I am guessing the fully open starboard thermostat is causing ECU to raise Rpm's to get temp up (water was 51 degrees) or at least this is what I hope is happening as I have ordered new thermostats. Would really like to know the relationship between port/starboard thermostats and which one is more important to the ECU but at this point I'm going to throw some new ones at it and see what happens.

[TownsendsFJR1300]

An open thermostat (especially in water that cold), will cause the ECU to raise the "cold start" idle. The engine is doing what it SHOULD do (on cold start up and NEVER warming up)

As you got it to run correctly for awhile, that's confirming the problem..

I would fix (replace stats) before doing anything else. Kinda chasing your tail till you fix a known, broke stat(s)..



As a side note, I went out a couple days ago (F150), water temp about 67F.
Cold idle stayed at 800 for quite awhile (700 warmed up-normal idle) and that's with fairly new thermostats..


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[HarrisonDawgs]

Towns,
Yes. Perhaps I failed to mention it but I did go ahead and order new stats as soon as I saw them. I basically confirmed it today. Manually reset the stat to closed position and took boat out again. Same water, same temp. Put about 45 minutes on it but never got it over 3400 rpm. Boat ran great the entire time. When I returned I pulled the stat cover to see and it was indeed closed tight. The bonus is that the motor is running strong and smooth and it would seem that all other factors are good since it is obviously not getting too warm at my normal cruise speeds. But I can verify one thing...when one stat sticks open and the other is closed, it idles extremely erratic and rough. I am also noticing a tad bit of slop in throttle cable now and I assume that can be taken out by adjusting the linkage but I won't attempt that until I have the new stats.
Thanks for your help and advice as it's always good to see what someone else can contribute.
Side note: ordered YDIS too, hope it works with my Win10.

[TownsendsFJR1300]

Sounds like great progress!

And the YDS works fine with Windows 10..

[99yam40]

running a motor with a known stuck closed stat for any extended length of time is not good for it., that head is going to get hotter than it should
try your best to avoid that in the future

[HarrisonDawgs]

Thanks! Stuck open though, not closed. It opens fine on test, just doesn't close. In the trashcan.

[99yam40]

I basically confirmed it today. Manually reset the stat to closed position and took boat out again. Same water, same temp. Put about 45 minutes on it but never got it over 3400 rpm. Boat ran great the entire time. When I returned I pulled the stat cover to see and it was indeed closed tight..

sounded like it did not open up after you forced it closed

[HarrisonDawgs]

99yam,
I quess I wasn't clear but both stats opened fine @ 115 degrees or so. Starboard stat wouldn't close on a cool down, port would close. I've never seen this before but I repeated the process dozens of times on the stovetop. First outing I cruised slowly for the most part. Heading back, I opened her up to WOT for a couple of minutes to compare speed/rpm. Apparently the sb stat opened and stuck. Idle went to crap as I was attempting to load on trailer. The next day I intentionally kept it below 3200 rpm (50 degree water) and apparently motor stayed cool enough to never open the stats, hence idle was good. Of course none of this is real important as I have junked both stats. Just posting my observations in hope it might help someone else down the road. I will add that I was very conscious of this and kept a keen eye on water pressure, temp, pisser, etc and I never made a single run for more than 8 to 10 minutes without stopping to give it a chance to cool (just in case).

[HarrisonDawgs]

Maybe I should have mentioned that I manually closed both stats in the shop before each outing. Fortunately my thermostats are on top of heads (2 bolts) and very easy to get to and my gaskets looked perfect. New gaskets will be installed with the new stats...hopefully tomorrow!

[99yam40]

just saying that aluminum blocks and heads are not as forgiving as the old cast-iron Automotive motors I grew up with.

a closed stat does not let water to flow into the head area and can cause problems quickly.

if you manually closed the stat and it was still closed when you pulled the cover to inspect it, I would think it never opened