Thermostat question

[Bald-N-Blue]

I understand there is a hard-to-tell difference between OBS and SD thermostats and using the wrong one causes all kinds hate under the hood.

I also remember reading something about some chain autoparts stores not having the proper part in their database for the SD?

Should I play it safe and go to the dealer parts counter? I've got a 203 degree t-stat in there now, I'm trying to chase down a stumble issue we think is related to elevated oil temps.

Almost forgot, this is for an early 99 PSD.

Thanks in advance!

 

[SPEEDDEMON31176]

I highly doubt your thermostat is the cause of your stumble issue. I would start by hooking it to a good scanner and getting codes and reading the live data. Also run cylinder contribution test and buzz test to start with. Check the color of the fuel in your bowl. Dark or black indicates poor injector o-rings. You will also want to look at the uvch under the valve covers, the valve cover gasket connections for damage, and the pigtails for damage. Check the IDM for water intrusion and check the main harness connections for loose pins, wire chaffing etc. Also check the IPR, CPS, and ICP pigtails for damage/loose connections. Also check the ICP for oil in the connector. These are all the basics to start tracking down your issue.

 

[Bald-N-Blue]

I'm a dumbchit, I keep forgetting to fill in my sig line with the mods I've done. And for the record, I agree with you regarding the thermostat not being the issue. If I had filled in my sig, you would have known I've got twin HPOP''s (among other things) and it's been live tuned. Both the pump builder and the tuner have suggested swapping out the hotter t-stat with a stock version, and it's easy enough to do. The stumble only happens when it's up to operating temps, and only at light throttle or idle. The best way I can describe the problem at idle is the "tone" of the injectors changes at random, almost exactly like randomly switching from a stock tune to a 140 race tune back and forth. Make sense?

I appreciate the response tho, it reminded me I was going to look at the UVC harness on the driver side. A while ago it got a little fubar'd and I was going to replace it but I haven't had time. And, I haven't looked at the ICP sensor for oil in the plug, so I'll look at that as well. So, thanks for reminding me to pull my head out of my azz LOL

I guess my next "mod" is going to be filling out my sig line so I don't look like a total idiot and waste everyone's time :doh: