Cranks perfect after sitting two days, renix 4.0

[dkmcgowan]

So I went and removed and plugged brake booster line. The brake booster is for sure hissing when pedal is pressed and my brakes haven't been feeling great, so that's a new project I guess!

 

But....

 

Capped off and unplugged the idle was still dropping.

 

It drops in park or drive.

 

It's like something bogs it down for a second or two and then idle goes back to normal and smooth then it will drop again and come back up.

 

As I said seems worse cold and seems to improve or happen less often if you start review and giving engine some gas and let it idle back down from there.

 

What should I replace or test next, other than the brake booster?

[cruiser54]

IAC been removed and gently cleaned?

 

How old is the O2 sensor?

[Eagle]

It's cranking just fine now, so far so good all day.

 

The idle is pretty perfect as well finally.

 

I do still notice when I first crank it and put it into gear and maybe rolling up to my first stop sign, the idle will drop low for about 1 full second or slightly longer and then recover back to steady idle.

 

You are still creating a lot of confusion by continuing to use the term "cranking" for when you mean "starting" or "firing up."

 

"Cranking" is what happens when you turn the key and the starter motor turns the engine until the engine fires up and runs by itself. An internal combustion engine can "crank" all day (until the battery runs down) without ever starting.

[dkmcgowan]

I'm sorry about terminology. I always said turns over and cranks, but it should be cranks and fires up.

 

So the firing up issue seems resolved. It's been 4 days now and I've been driving every day, so that issue is solved! I think it was a combination that fixed it, cps, new plugs, new wires, new injectors, ground clean up...

 

Now the last issue.

 

Low idle.

 

I can start another thread, but the latest is I think the idle is low mainly when cold. I verified this morning again and it stopped once it warmed up.

 

It never dies or anything, just drops idle until it warms up.

 

O2 is oem and brand new, cleaned iac, maybe not very gently, missed that part, but it seems to be working.

 

I have a new oem egr installed as well, but not that vacuum thingy it hooks too.

 

I was going to order a fuel pressure gauge and then was thinking iac, but the worse when cold makes me not think iac.

 

I don't think I have any vacuum leaks. I tightened intake bolts, replaced all hoses, new vacuum canister, it was leaking, new brake booster, it was leaking, new map sensor line made out of brake line.

[1989 Eliminator]

Again... Look at the last few pages of my rough idle topic in my signature.

 

Id suggest adjusting the throttle body screw AS A LAST RESORT..... it is facing the firewall I believe on the throttle body and has a metal cap on it. Take it off and screw it in/out until idle is good. But this is not the correct fix for idle. Vacuum leaks, low fuel, dirty injectors, bad grounds, bad sensors, incorrect voltages all come before this adjustment screw. (I know you checked and replaced a lot already).

 

http://comancheclub.com/topic/42581-renix-dead-spot-and-idiling-low/page-8

[dkmcgowan]

I've read your whole post...  I still have a few things left to try before I get to that.  I'm seeing the right voltage I believe at the O2 sensor, but it feels now like it's not heating up fast enough.  It's a bosch unit.  I've read of other people just getting bad ones.

 

I am ordering an NTK one now just to see.

 

Then I need to test my CTS and see if maybe it's not working correctly, check the throttle plate adjustment to make sure it's not too open, and maybe just get an IAC and/or a TPS just for fun since they are original.

 

If that all failed I would probably look into your adjustment.

 

I'm hoping on the O2 sensor right now, positive thoughts

[cruiser54]

I've read your whole post...  I still have a few things left to try before I get to that.  I'm seeing the right voltage I believe at the O2 sensor, but it feels now like it's not heating up fast enough.  It's a bosch unit.  I've read of other people just getting bad ones.

 

I am ordering an NTK one now just to see.

 

Then I need to test my CTS and see if maybe it's not working correctly, check the throttle plate adjustment to make sure it's not too open, and maybe just get an IAC and/or a TPS just for fun since they are original.

 

If that all failed I would probably look into your adjustment.

 

I'm hoping on the O2 sensor right now, positive thoughts

Bosch now? 

[dkmcgowan]

Yes... the only sensor I have gotten that wasn't nos mopar, couldn't find one. It's from a parts store.

 

Ordered up the ngk/ngt one from amazon, will be here tomorrow, will try that and see.

[dkmcgowan]

I installed the ntk sensor tonight, fired it up, idle still drops. So it fires right up, idles shoots up, comes back down, then slowly drops to where it should be, then it settles for a half second, then you feel feel it drop the idle, run a little rough, fix itself, drop the idle, run a little rough, fix itself, etc...

 

I also tested the cts and mat/iat. It's about 75 degrees outside, engine was hot about 4 hours ago, ran it only for 20 seconds to test new o2 sensor. I got about 1200 ohms from both sensors, they matched, which is about 100 degrees, which seems about right to me from the chart.

 

I need to test them both again when hot, so will test them after I drive to work tomorrow.

 

I unplugged the iac while it was running to see what it would do. It might have fluctuated less, but hard to tell, I couldn't catch it to try and unplug when it was running good, but I don't think unplugging it really made any difference at all.

 

It also was doing it today a bunch when warmed up, so it's not just when cold.

 

I'm thinking of orseeing an iac next.

 

I ordered a fuel pressure gauge today. I have new 746 injectors and new oem nos regulator on a clean rail with no leaks. I also have tons of power off idle and engine runs great off idle, so not thinking fuel pressure but will be able to check on Thursday when it comes in.

[1989 Eliminator]

I don't know man... I had the EXACT same issues that you are having. Everything I did seemed to fix it but there was a lot that I changed.

 

Have you indexed your distributor yet?

 

I replaced there components on mine because of this issue and just becuase its a 26 year old Jeep...:

 

MAP

IAC

EGR

TPS

CPS

Injectors (replaced with 746)

ICM (ignition control module)

Spark Plugs

Spark Plug Wires

Distributor Cap

Ignition Coil

Intake/exhaust manifold gasket

new air filter

New cam cover gasket (silicone)

Replaced all relays

O2 sensor BOSCH

 

**All of these replacements did not happen all at once. Some were replaced several thousand miles apart.**

 

Other things I did:

 

Upgraded my engine and chassis grounds with new thick wire and new locations

cleaned IAC and throttle body

ultrasonic cleaned 746 injectors

Moved vaccum canister from front bumper to under coolant bottle by the firewall (made vacuum lines shorters and replaced some lines with new tubing)

Cleaned ALL electrical connectors and applied di-electric grease on pins

Various voltage and resistance tests like you are doing

Added a fuel rail pressure guage

Sealed the PCV tubes coming out of the cam cover better

Upgraded to a dual diaphram brake booster and master cylinder

Eliminated the "cold air valve" in the opening of the airbox (it is a valve for when it is cold outside to heat the incoming air but is not needed)

I have a CAT and muffler that is about 4-5 years old

Indexed distributor

Moved the idle Air screw on side of throttle body

[cruiser54]

I installed the ntk sensor tonight, fired it up, idle still drops. So it fires right up, idles shoots up, comes back down, then slowly drops to where it should be, then it settles for a half second, then you feel feel it drop the idle, run a little rough, fix itself, drop the idle, run a little rough, fix itself, etc...

 

I also tested the cts and mat/iat. It's about 75 degrees outside, engine was hot about 4 hours ago, ran it only for 20 seconds to test new o2 sensor. I got about 1200 ohms from both sensors, they matched, which is about 100 degrees, which seems about right to me from the chart.

 

I need to test them both again when hot, so will test them after I drive to work tomorrow.

 

I unplugged the iac while it was running to see what it would do. It might have fluctuated less, but hard to tell, I couldn't catch it to try and unplug when it was running good, but I don't think unplugging it really made any difference at all.

 

It also was doing it today a bunch when warmed up, so it's not just when cold.

 

I'm thinking of orseeing an iac next.

 

I ordered a fuel pressure gauge today. I have new 746 injectors and new oem nos regulator on a clean rail with no leaks. I also have tons of power off idle and engine runs great off idle, so not thinking fuel pressure but will be able to check on Thursday when it comes in.

89Eliminator is making a couple good suggestions.

 

Be sure the distributor is indexed first. Then, we can go on to the idle air bleed adjustment. 

[dkmcgowan]

I have done most of that list except...

 

IAC
TPS

ICM

Ignition Coil
Intake/Exhaust gasket (but I did tighten the bolts and don't seem to hear anything from exhaust manifold at least)
Cam cover gasket

 

I didn't clean my throttle body as good as I probably could have.  I didn't take it off.  So I plan to remove the throttle body, clean it really good, check the stop screw and make sure it's set correctly.  I just ordered a new throttle body gasket, oem IAC, and oem TPS.  I plan to do all that first.

 

Then I can rule that all out.

 

I'm hoping not intake/exhaust, don't feel like taking all that apart.  I also have a problem.  I'm the type of person that if I take it all off, I will want to go ahead and get the intake cleaned, then I will want to go ahead and put a new exhaust manifold on it because I have it apart.  Then since I have such easy access to the head and I'm half way there, might as well pull it off and get it cleaned up, checked and rebuilt, and so on and so forth...

 

It seems to idle more consistently low now that I replaced the Bosch O2 sensor with the NTK one.  I felt like before it was moving up and down and moving around more, but now I'm pretty much steady low and running a little rough.

 

Not sure if that means the NTK O2 is working more consistently correct, and exposing the other issue more like the IAC or TPS, or if that means the Bosch was working better than the NTK.

[1989 Eliminator]

If you did not replace the TPS with an OEM quality brand and not a typical auto parts store brand then this could be definatly the issue. The TPS is very finnicky if you do not get a good quality brand. Also you have to make sure the TPS is set correctly but I think you already know how. If not look in cruiser 54's tips.

[dkmcgowan]

If you did not replace the TPS with an OEM quality brand and not a typical auto parts store brand then this could be definatly the issue. The TPS is very finnicky if you do not get a good quality brand. Also you have to make sure the TPS is set correctly but I think you already know how. If not look in cruiser 54's tips.

 

Not sure, it's the IAC and TPS from when I bought the vehicle, so not sure if they are OEM original or PO changed them at some point with parts store versions.

 

They are ordered up, fingers crossed...

 

 

Also...  I did set it from cruiser tips, and it set to the correct voltage, but that doesn't mean it could not still have issues.

[1989 Eliminator]

Either way..... if it is orignal then you have a ~26 year old TPS sensor and if the PO changed it, he could have bought a crap brand. I hope this fixes it!

[dkmcgowan]

This post seems to give a different way to do the TPS

 

http://comancheclub.com/topic/11634-renix-throttle-position-sensor-tps-testing-adjustment/

 

It says if you had 5 volts, on a M/T it should be .8 and if you have an A/T it should be 4.2, which is very different than what cruiser says which is if you had 5 volts it should be x .17 and be always .85.

[dkmcgowan]

Just realized that is probably because TPS on A/T has two connectors, that post is confusing...

[dkmcgowan]

When I pull the throttle body to clean it, was considering using a 1/8 NPT tap and instead of a plug pike cruiser, just do a nipple so I can easily just use vacuum hose from my throttle body to my map sensor.

 

Any down side to this?  Not sure why they didn't do this before.  On all carbs I've every worked on it was press fittings or threaded, never rubber piece to push into the hole.

[cruiser54]

When I pull the throttle body to clean it, was considering using a 1/8 NPT tap and instead of a plug pike cruiser, just do a nipple so I can easily just use vacuum hose from my throttle body to my map sensor.

 

Any down side to this?  Not sure why they didn't do this before.  On all carbs I've every worked on it was press fittings or threaded, never rubber piece to push into the hole.

Not a bad idea. 

[dkmcgowan]

So I got my fuel gauge in tonight. I hooked it up and cranked it, I got about 28-29 psi at idle, moved between those two. I then unplugged vacuum to regulator and it went up to maybe 36 psi.

 

Is that good enough? I could try again with ballist thing bypassed.

 

It's a new oem regulator.

 

Also, it's pretty much running bad all the time now at idle. Not as much flucatuon, just rough idle. I think the NTK o2 sensor made it worse.

 

Not sure if the o2 sensor is working now and making the real issue more evident, or if I should put the Bosch back in.

 

Iac should be here Saturday, plan to clean throttle body off intake, set stop, put nipple in with tap for map sensor line, new base gasket and new oem iac and give it a try.

 

I also have an oem tps coming in, probably won't be here until next Wednesday.

 

The getting worse with o2 confuses me, figured it would get better or stay the same.

[cruiser54]

Your gauge could be off.

[dkmcgowan]

It'd a brand new gauge, but was cheap. It shows in have pretty decent fuel pressure and so that's probably not it.

 

I went and ran it with egr disconnected, same symptoms, I then ran with o2 sensor disconnected, same, then put in the old Bosch o2 sensor and it was also the same.

 

I put back in the ntk and assume it's not that.

 

More to come this weekend.

[dkmcgowan]

I got the iac in the mail today and a new base gasket. The tps won't be here until Monday.

 

I took the throttle body off, going to do the mod with the 1/8 tap, will take pictures and make another post to help others.

 

I adjusted the stop. It was at least two full turns or more open too much. I twisted until it was no longer being hit, then opened it up just until I could barely see light all the way around the throttle plate, so I knew it wasn't hitting anywhere.

 

So that was wrong for sure.

 

This iac is aftermarket for sure, cheap brand.

 

The tps looks original and 26 years old.

 

Question about cleaning throttle body. I started with throttle body spray and toothbrush and this probably won't get it perfect. If it was a carb, I would be soaking it over night in cleaner. What is the normal for throttle bodies?

 

I've also done carbs with regular pine sol, cleans it but dries it out pretty good, but works.

[cruiser54]

You're doing great. Toothbrush and cleaner is good. 

[dkmcgowan]

So I soaked the throttle body in 50/50 pine sol and water.  Then I dunked it in soapy water and brushed it off with a copper brush.  It got pretty clean.

 

I then put a light coat of oil on the whole thing and wiped it down.

 

I then tapped the hole where the rubber thing goes for the MAP sensor with 1/8 npt tap and threaded in a plug.   It fit great, no drilling required, whole is already perfect size.  I then installed a nipple from advanced auto that is 1/4 nipple to 1/8 mnpt thread.

 

Then a couple feet of 7/32 vacuum hose from that nipple to the MAP sensor and you are good.

 

Much easier maintenance in my opinion.

 

I also adjusted the throttle body stop, it was opening butterfly a couple of turns too much.

 

My new oem TPS doesn't arrive until Monday afternoon, so I installed the original TPS again with the new IAC.

 

I wanted to crank it and see if there were any differences.

 

I went to set the original TPS and went by the FSM I have.  It says for auto to use 4 prong connector instead of the 3.

 

The 4 prong connector had 4.63, and it says to do .83 for output, so that had me set it to 3.84, which I did.

 

I then went to check the 3 prong connector just to see, where cruiser says .17 is where it should be.

 

It is 4.88, so that means it should be set using .17 to  and end up being .83

 

When I checked it, it was closer to .66, which would be .137 instead of .17.

 

So I cranked it up.  It idled better than before.  It seemed less rough.  I still have the fluctuation though, before it would drop really low and run rough, go from low to where it should be, but mainly stay low.  Now it seems to idle closer to where it should, but it is jumping up and down more, so more going up from where it should a little bit and back down, but fluctuating more than before, but overall feels better, but still not right.

 

So I'm hoping I made some things better, but still need the new TPS and that I just had many problems at once.

 

How should I adjust the TPS?  For sure just do it to the 3 prong connector for manual or auto, or should I have done it with the 4 prong connector like I did?

 

Before these changes I had adjusted it based on cruiser write up to .17 on 3 prong connector, so all my differences in running could be from my different TPS adjustment and not the other stuff I did, who knows.

 

 

Here are some pictures....