Ryan_Colorado

1990 Renix I6. I am having high-idle based on sound and feel. I'm considering installing a tachometer so I can get more exact. Before then, I'm trying to identify my next steps. Here's lists of what I have done, and what I haven't done.

Here is what's been done so far.
- Replaced all vacuum lines on the drivers side with the two dorman kits.
- New Intake/Exhaust manifold gasket
- New Throttle Body gasket
- TPS replaced last year, and just adjusted by my mechanic this week (I'm assuming to correct voltage)
- Cleaned EGR Valve and got a replacement doughnut from the junk yard
- Cleaned IAC

Things I haven't done:
- Really examined the butterfly position after having it all apart
- Replaced or cleaned MAP Sensor or EGR Solenoid
- Replaced the MAP hose as per Cruiser54 (wish I had seen this when I had the TB apart!)
- Replaced IAC (at least I don't think I did, it's not in my notes)
- I haven't done anything with the canister or it's hoses. I previously trimmed the cracked end of one of it's hoses, but did not replace

Suggestions where to go next?

Thanks!

- Ryan

Ryan_Colorado

Here's my plan for myself in this order:

1) Clean MAP Sensor
2) Check MAP voltage
3) Re-Clean IAC
4) Check TPS Voltage
5) Adjust throttle butterfly set screw
6) Retorque manifold
7) Consider replacing MAP and/or IAC (My gut has said IAC for a long time, but I haven't thrown parts at the problem just yet, other than the tubing which needed to be done anyways.)
8) Cruiser54's instructions to replace MAP hose and upgrade grounding.
9) Continue search for vacuum leaks (really ongoing)
10) clean/inspect MAT Sensor
11) clean/inspect CTS Sensor
12) Upgrade to better TPS

cruiser54

Do Tips 1,3,4, and 5 first.

Ryan_Colorado

Thank you Cruiser! I'll add that the idle problem is really in Park and Neutral. Most of what I've read suggests vacuum leak or IAC. But I am trying not to throw parts at the problem.

cruiser54

Get the Tips completed first.

PatHenry

x2 (or x1000) on doing whatever Cruiser suggests.

Ryan_Colorado

Is there an x^Infinity character?

Ryan_Colorado

I think I have possibly diagnosed a bad TPS. The "A" Voltage is 4.66. The "C" Voltage barely reads. Basically, I think the arm on the back of the TPS needs to be adjusted further than what it can be when it is installed. I can manually push it down to reach my target voltage of .79. I can remove the TPS and get push the arm to reach .79. But, I can't rotate it far enough to get it where it needs to be. In fact, it barely reads voltage at all.

I am also going to put a new o-ring on the IAC.

New TPS?

Ryan_Colorado

Installer error - wasn't set correctly to move with the throttle. Now it's a perfect 0.83. New o-ring on IAC. Working through Tips 1,3-5.

Ryan_Colorado

Update on Cruiser's tips:

Tip #1 - I believe a previous owner did this. The extra firewall grounding wire is in place. The extra battery ground was there when I purchased but I removed two years ago. I will replace. I was not able to remove the dipstick ground bolt or stud. I was afraid of rounding the end of the study with the 7/32" wrench. I do not want to take on cutting and putting on new ends at this time. Also, the battery ground was moved to this location.

Tip #3 - Will be ongoing, but I have cleaned every connector I can find and access, including the two below the ICU and the 10-pin by the air box (which appears to only have 6 pins internally). I have cleaned 4 relays near the ICU and one on the driver-side fender.

Tip #4 - In process. Need to buy OxGuard tomorrow. Disassembled and cleaned.

Tip #5 - I got a very consistent 0.7 Ohms. Shaking the harness didn't matter. Held consistent.

Tip #6 - I spent a little time trying to trace the wires, but everything has been wrapped and re-wrapped that it seems like a much bigger job right now than simply following the brown/white wires. And I'm not confident that it hasn't been done already.

Ryan_Colorado

Update on Cruiser's tips:

Tip #1 - I believe a previous owner did this. The extra firewall grounding wire is in place. The extra battery ground was there when I purchased but I removed two years ago. I will replace. I was not able to remove the dipstick ground bolt or stud. I was afraid of rounding the end of the study with the 7/32" wrench. I do not want to take on cutting and putting on new ends at this time. Also, the battery ground was moved to this location.

Tip #3 - Will be ongoing, but I have cleaned every connector I can find and access, including the two below the ICU and the 10-pin by the air box (which appears to only have 6 pins internally). I have cleaned 4 relays near the ICU and one on the driver-side fender.

Tip #4 - In process. Need to buy OxGuard tomorrow. Disassembled and cleaned.

Tip #5 - I got a very consistent 0.7 Ohms. Shaking the harness didn't matter. Held consistent.

Tip #6 - I spent a little time trying to trace the wires, but everything has been wrapped and re-wrapped that it seems like a much bigger job right now than simply following the brown/white wires. And I'm not confident that it hasn't been done already.

cruiser54

Thanks for the update!!

Ryan_Colorado

Drove it today. Best it's felt in the two year's I've owned it! No high idle in park or neutral. Very smooth shifting through park to drive. Didn't want to go on it's own with foot of the break. And, I don't think it quite hit 210, even though it was upper 90's outside. I did forget to grease the coil/ICM contacts, but that's a 10 minute project.

I plan on driving for a week or so to figure out what my MPG is now. Before it was about 11. I will update then.

Thanks all!

cruiser54

What do you attribute this to?

Ryan_Colorado

Well... I can't say vacuum lines in this case b/c after the vacuum line replacement I've done so far, it was still an issue. Same for the manifold gasket. So, I'm guessing either the TPS wasn't set correctly, the IAC needed another round of cleaning, or some electrical component along the way was interfering with their operation. But my real thought is that all three were contributing in one way or another for an effect in summation. Which I think is the real lesson of following your tips, especially when vacuum and poor electrical engineering are concerned. A little loss of pressure or voltage here, a little loss there, and the net effect is poor performance. You really do need to do 1-5 (and I'd add 8 too) before making any judgments about what is or isn't working. I appreciate that more now.

It's one of the reasons I'd like to adapt your text into a checklist format. Your narrative is fantastic at the "What, How, and Why," - but I need another tool that's just a list of the "What" so I can keep track. But maybe that's just me!