Hi people......1st post here, but been on this site off/on for 2 months trying to get issues with my car fixed.

97 Protege, 1.5L 250,000kms

Rough idle....to the point of stalling. Thoroughly cleaned throttle body, egr, air valve and all passages. Can't find any air leaks. Vacuum gauge shows steady reading of 24. New plugs, wires, fuel filter.

Car is better than it was, but now cold weather is upon us, it's much worse. Tried to speed up idle, and I fooled with throttle stop screw. Removed TPs....spayed/cleaned it in electronic cleaner. I had crazy ohm readings before I did this.

The car is a little better when warm, but I still "cylinder 4misfire" while dring on highway. Car is still terrible when cold, first 10-15 minutes, but better than it was.

Here's my issue. Haynes manual gives directions for 95-96 protege, but for 97 and newer, bring it to dealer, as they use a special break out box to set them.

With TPS on car, and throttle closed, I set TPS at 0.9V. gives me around 4.5V at WOT. Car runs better warm, but is terribl cold (little better than before I played with it). Also, if I turn on heater fan when cold, idle slows to point of engine shaking, and doesn't recover.

So, I've played with 1. stop screw 2.air screw, 3.TPS.

My questions are.
1. Anyone know how to set TPS? I'm assuming you just look for a low voltage at closed throttle.
2. How is this related to Stop screw? I presently have it only screwed in enough to just touch the stop, (spring tension). Other models look for continuity between pins A and C (3 wire TPS)...and no continuity after after you open it a hair with feeler gauge. Book says this one is different. I don't get any continuty between A/C with throttle closed, and I don't think I'm supposed to.

I think I'm on right track, but have it set wrong. I think I need to open throttle plate a little, then set TPS.

Thanks for any assistance/direction any one can provide.

 

yeah, i would open it a little and then set the TPS. if that doesn't work, drive the stop in a little more and open it with a feeler to set it again. i don't recommend a lot more work from there, because i hate electronics and when i can't do it the first couple of tries i hand it over to a shop. if you want to brave a little more work, you are on your own. i know that the stop is supposed to hold a little more than just spring tension, but i am not 100% sure on how tight it needs to be.

 

Browsing around the forum.....I found a link to a 626 manual. It has the same TPS. I show 4.96 V on signal line....so I need to set 0.5V at closed.


I had a go at it for 3 Hr. tonight. Drove screw in farther, drivability was good.....didn't slow with heater fan on....but idle was too fast, and I couldn't bring it down with air screw. Backed it out some.....reset TPS......idle is slower...but almost stalls when I turn heater on.

So...I'm thinking I have to find that lucky spot for the stop screw in between. I have a habit of learning things the hard way....At the time I first used the stop screw to try to adjust idle, I figured it would be easier to recover in comparison to air mixture screw!!!! Won't forget this one.

 

Update
Put the stop screw in another 1/2 turn......set TPS @0.46V....turn it for a run to warm it up.....hooked up tach.......set air screw till I got steady RPM just shy of 800.

Car pulls better than it ever did since I owned it, looks like I didn't burn as much gas this morning on way to work (100km each way), and now idles steady with elec accessories (heater) on. Like a new car. It was getting that bad, I was nervous regarding head gasket.....and I don't think I would've spent that kind of money on it, as it's starting to show it's age.

Anyways, info throughout these forums gave me enough info to get it going properly.

 

Can anybody offer any more information on this issue? My 1.5 is having very similar symptoms and I think I need to make these adjustments.

I always thought the screw facing vertical on my 1.5 was the idle adjustment screw? Am I wrong? This thread states it is near the throttle cable, not on top?

Please help. Pictures would be awesome!!!