Crimmy

Hey guys. Been more or less trouble free for awhile. Rather ive been broke and my issues have been tolerable. =P

So if anyone is familiar with me my idle, throttle body, and iac were huge issues and i got it more or less tolerable but ive replaced IAC 6 times now. About once a month or so. What is happening is the IAC's pintle will extend so far that the plastic valve breaks off. It is the same thing every time. It seems to be related to either an emergency hard brake where the rpms very suddenly drop or a sharp increase in rpms by flooring it once its warmed up and the oil pressure has gone down. >.> Dont ask...its a my jeep thing.


And lastly the rubber elbow for the crank case vent tube right on top of the valve cover keeps splitting down the side. Its irritating because i have to have them ordered in from a store pretty far away from me even living in portland oregon a major city... Waste of time and gas moneys.

So it seems to be a stress or pressure crack in the rubber. From being severely bent but i cant immagine my engine moves that much. Or from very old and dry rubber but i dont see any cracking in the rubber or whitening. It still looks shiny and black and very smoothe.

The IAC's are from autozone. And that vaccume harnesses were from napa. Let me know any thoughts.

DFlintstone

Maybe try an IAC from somewhere else? Maybe rockauto.com. My new to me 90 came with a busted vent grommet. I happened to have a grommet here that fit and some 1/2 inch copper so I did this. That's 5/8 clear vinyl tube connecting the original tube to the copper. Potential problem though. The original had a section there that starts large and tapers to the 1/2 inch tube. That might actually matter as air shrinks so much when it cools, Idk about that. If you do, do that and suddenly have more dripping from the rear main area, you might go back to stock.

Stabsthedrama

Just going to copy and paste an old reply I had made on the subject, should be useful:

This is the world of renix/blowby. Clean out all hoses/pcv, change the air filter - and learn to live with it. They all have it. Period. Minimizing it is key, and yes, the main thing you can do is replace the hoses/grommets from the VC and check all other hoses connected to the airbox.

Also, as per cruiser's tip(s) - you'll probably want to do the valve cover gasket, and while you have the cover off you should give it a good cleaning (air compressor helps), and also trim down the 2 metal drain tubes that are connected to the top of the inside of the cover. These tubes go down too far and suck up oil a bit too greedily. However, in his tip he suggested cutting the lines down as well as drilling holes at the top of them - mine actually already had holes (and they looked stock) but trimming them down by about 1/2 with an angle grinder and doing the gasket (felpro) seemed to help quite a bit. I still get oil in the airbox, but owell - it ain't gonna hurt anything, and it's minimized quite a bit.



I'm 99% sure the hose COMES with the grommet, but you can order a grommet to make sure - I now just have an extra grommet.

Rockauto:

1989 JEEP CHEROKEE 4.0L 242cid L6 :
Emission : PCV Valve / Crankcase Ventilation Grommet
Price: $2.23
DORMAN Part # 42088 {#53004722} ID: 0.229"; O.D.: 1.314"; Thickness: 0.823"
PCV to Valve Cover

PCV Valve / Crankcase Ventilation Hose
Emission : PCV Valve / Crankcase Ventilation Hose
Price: $7.41
DORMAN Part # 46005 {#4762592} Crankcase Vent Tube
Crankcase Vent Tube

67 GMC

Have you checked your ASD (Autoshutdown) / B+ LATCH relay? It's supposed to keep power on for a few seconds after you turn the key to off so that the IAC pintle extends. I would think that after putting in 6 IACs, there's something else going on. Pretty unlikely you would be able to get 6 bad ones. I assume your throttle body is very clean after replacing the iAC so many times. Is your Jeep hard to start after shutting down for a few seconds? Any chance the throttle butterfly can hit the pintle? Maybe the stop screw isn't adjusted properly. I can't picture where the pintle is relative to the butterfly though-I could be way off.

Crimmy

There is no way the iac pintle could hit the throttle body. At least not the butterfly valve part of it. It has its own little orifice that it could hit the wall of the throttle body.

Im pretty sure the stop screw isnt set right but that is due to another issue altogether. The jeep is slow to start in the morning when it is cold. Takes a good 3-5 seconds of cranking before it kicks on. However when its warm if i shut it off and start back up it kicks on right away. The reason i know the screw isnt set right is because the idle is already too low When i had it set properly it wouldnt stay running without my foot on the gas. it was choking itself out. But once warmed up it ran perfectly. So i had opened it up and it worked GREAT when cold. Perfect idle of 750-800 lots of throttle response. However once it got warm the idle was much higher around 1200-1500. I could coast or idle at 35 without touching the pedal. So i found a happy medium where it works ok. Its still too low in the morning but not enough that its causing problems.

Is that relay you spoke of applicable to a renix?

DFlintstone

Renix has no ASD relay, but the latch relay is the third one back in that row of four. Yea, I read somewhere it provides power for the IAC to reset after shutdown for the next start. The stop screw should just keep the throttle plate from hitting the TB, (and making a gouge/getting stuck). Then the IAC controls the air flow from there.

Btw, you never want to plug in an IAT that isn't mounted on the TB. I read if you let it extend more than something like 1/4 inch, that may ruin it.

67 GMC

I think the ASD/B+Latch are the same terms aren't they? Renix lingo is B+ but I was talking about the same thing anyway. It extends the pintle after you turn the key off.
I read the same thing about extending too far. If the pintle is extended more than 0.25 inches, it comes off or can't go back in.


As I said, after 6 replacements, there has to be something else wrong other than the IACs. These things last quite a few years at least before dying and usually they seize.
One thing you could try: When it's idling good, disconnect the IAC and see if it stays good. That will keep the pintle where it was (it's really only used for idle situation (coasting, foot of gas etc).


OP-Ever try adjusting your throttle cable? There's a youtube video on that.

Firehawk068

Soooo.....................This guy in the video is talking about adjusting the throttle cable, but he is showing you how to adjust the "TV" cable for the transmission.....


As far as I know, there is NO adjustment for the throttle cable, except maybe to bend the cable bracket in some way...........

DFlintstone

I don't think so. (not sure...) A while back looking at wiring schematics, I came to the conclusion the Renix fuel pump relay deals with allot of the stuff that goes through an HO ASD relay.

Who wants "automatic shutdown" anyway? We have enough to deal with without that!

Crimmy

Can you show me a picture or tell me where that relay would be and a testing procedure for it? Installation of these things is just stick it in or does the iac need to be preset somehow?

Also in that video it is showing a non renix. My throttle cable is on the back of the throttle body and uses a much different system. There is no bracketry or clips for my cabl and theres only 1 cable in there. Renix also has its own throttle body that is unique to the renix which is why finding one thats been bored out is near impossible because nobody wants to deal with the headache that is renix! =P Still though its been reliable if anything.

67 GMC

There's lots of us with Renix Jeeps. I've got an '87 Laredo. The adjustment for the cable is the same as the video. The cable is just further back. Has the same button and action. Lots of posts on that.


Here's a picture of the relays. They are all the same type as far as I've been told. You could switch the A/C clutch relay for the B+latch relay as a test.