dkmcgowan

I just went and set it back using the .17 from cruiser tips, so 4.88 x .17 = .83. I then drove around the neighborhood. It's idling pretty constant now, but low. Around the first notch from zero. But... It's pretty smooth idle, even that low. So the cleaning, new MAP sensor line and nipple, adjusting on stop screw, and new IAC did help. One or all of those things were making the rough idle I believe. Now it's truly just low idle, I think... Not much driving time for testing here,but initially it appears that is the case. I then set it again using the 4 prong connector, doing the 4.63 x .83, which makes the other 3 prong connector .67 instead of .83 and drove it around. It pretty much felt the exact same, no difference. The idle was pretty smooth and still just low. I'm thinking not all the way bad TPS, not a TPS not working correctly. Hoping the TPS on Monday solves it all right now. Still curious on best way to adjust TPS, but unless I hear otherwise, I will go with the cruiser tip of .17 on 3 prong connector when I get my new one in on Monday.

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....

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.

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.

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.

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.

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

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.

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.

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.

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.

I purchased a new master cylinder this weekend from NAPA, M2960. It looked just like my original, bolted up, worked fine, everything seems good. But... There was an extra part included in the bag, it looks like the one below. That picture is also from NAPA but it is a part included in their master cylinder rebuild kit. What is this for and do I need it for anything? It almost sees like it could be used to convert to work without a booster maybe?

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.

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

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.

I probably should have done it this time around but stuck with stock. Drove well this morning, I also adjusted the rear brakes, twisted the star things up until when I spun the tires hard they did one full rotation. I did over tighten them once and forced them to loosen up, it worked but was hard, later realized I should have been pushing that tab forward to allow it to go the other direction, hope I didn't damage anything, might take drum off and check. Also seems like I need to bleed again with thag front wheel open and brake light on, but that seems like a pain and I would need 3 people. Also seems like front caliper would sucks in so much air while waiting on me to bleed the rear again. Progress though.

I think my booster was working, but probably going out. It was hissing constantly when pedal was depressed. For others that try, I do not believe on a renix 4.0l it's in anyway possible to remove the brake booster without the master cylinder. I tried and bent up some brake lines a litte, but was able to get them back in place I think. So I ended up just getting a new master cylinder as well just because I was already doing it. Got it all put together and bled all the brakes, think I got them good. Brakes worked better, but still a little soft. I then discovered that the rear brakes were pretty far out of adustment. I tightened them up until if I spun the wheel off the ground hard it only made one full rotation. Brakes are better now. I then read that I have to do some other special bleeding process again with the front caliper open to open the rear valve. I have not done this yet. I feel I need a 3rd person to just watch fluid to get this done. I hate bleeding brakes.

Plan to try tomorrow. I've always thought bad booster meant hard pedal. My pedal is soft, but the vehicle isn't stopping and you have to push really hard, but pedal seems soft, and a constant hissing if your foot is on pedal. I know booster works somewhat because it's rock hard with engine off, crank engine, pedal goes down, but starts hissing. I guess somehow it's possibly to have soft pedal with bad booster?

Can I replace brake booster in my 89 4.0l without removing brake lines from master cylinder? I just bled that thing forever when I did brake lines and I hate bleeding brakes. I'm not sure if there is any slack really to pull it back and remove from those mounting bolts on booster. My booster is hissing with pedal down, can hear it in cab. Stops hissing when you let off brake. Not looking to upgrade now like I know many do.

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?

So went out again after it was sitting for a while and it fired right up. I believe along the way I fixed the cranking issue. So with the engine kinda cold, cranked it up, idle goes up, slowly comes down, then it goes to where it should be, then it goes too low. I put it on gear but never gave the engine any gas. The idle stayed pretty low, towards the bottom line, enough to make engine rough. I started giving it gas review it up and letting off, the idle then stabilized more. So it's worse if you just never give it gas. Also, sitting in driveway listenig, I noticed that while break pedal depressed there is a constant hissing sound, and I've thought my pedal was soft. I thought I tested booster by pedal being hard when engine off, and gets soft when you crank, but it sounds like a vacuum leak with your foot on the pedal, might be not related.

I did, got it to a perfect .17 of the main voltage, ended up at .83, it was 4.83 x .17 was .829 so I'd did .83 It idea high when I adjusted when vehicle off like you said could haopen, so I adjusted while running and got it just right, depending on the accuracy of my volt meter of course.

I replaced all the injectors today with 746 injectors. I also put on a new oem regulator, and put in new ngk plugs gapped to 0.35. When checking the wires, I did notice one on the distributor wasn't pushed in all the way, so I might have had an issue there. 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. It does it worse with the AC on. It recovers and idles fine, but assume I shouldn't notice if all was perfect. Done most cruiser tips, no vaccum leaks, manifold bolts tight, good compression, cleaned iac, adjusted tps, all updated grounds, soldered harness ground and ohms are good at sensors, all new vacuum harness, all new plugs, wires, distributor, rotor, new oem egr, new 746 injectors, new oem regulator, new brake line used for map sensor, new oem map sensor, new oem cps, new oem o2 sensor, cleaned electrical connections, cleaned coil connectors and bent out springs It's running good, just seems like it's slower than it should be to adjust the idle. I plan to check the the throttle stop tomorrow and then was wondering if it's a tps or iac going out or just how the renix is?

Got it all installed today, seems like no leaks and a success!

I just put all the injectors into the rail and the regulator, got it all ready to reinstall. I went out and took a look at the manifold holes again. I decided to just get a small screwdriver and try to scrape the crude towards the manifold and clean it out. This worked for the most part. I got most of the crude scraped out and then twisted up some shop towel and twisted it into the holes. I only did two of them because some of the crude definitely fell back into the cylinder. Not much, I bet I scraped 70% of it out and little pieces fell back into the cylinder. I plan to fire up the vacuum cleaner tomorrow and see if that will help, but don't think it will help much with the hole being so small. Will a few small specs of carbon buildup hurt the cylinders? Isn't it most likely already in there as well or at least will just burn up next time it ignites? I felt I had to clean it at least a little or it wouldn't seal correctly, otherwise I would have left it alone.