Hello,

My MAP vacuum hose is cracked on my 1989 Jeep Cherokee 4.0 I6 and I want to replace it. I read up on people using 3/16" brake line as a "permanent fix" since the original part is no longer available. My questions are...

1. How do you attach the brake line to the MAP sensor nipple itself? and
2. How does the brake line go into the existing grommet on the throttle body? Is the existing hole big enough? What keeps it in place?
3. What goes on the two ends of the brake line?

Thanks in advance.

 

CRUISER'S MOSTLY RENIX TIPS

THROTTLE BODY TO MAP SENSOR HOSE FIX

JANUARY 23, 2016 CRUISER54 45 COMMENTS EDITThe Renix throttle bodies have a strange and failure prone connector on the side where the MAP supply originates and then runs up to the MAP sensor located on the firewall. This hose/pipe assembly is no longer available for purchase.

The real kicker here is how critical this line is in supplying the correct vacuum signal to the MAP, the most relied upon sensor for the ECU to read regarding air/fuel ratio. Any cracks, melted spots, or loose rubber connectors can cause major starting and driveability issues.

There’s a simple fix though. All that’s required is a 1/8” NPT tap, a new throttle body gasket ( Napa FPG 60742 ), a vacuum fitting (Napa 05703-B102), two vacuum elbows (Napa CRB2670), and a length of new plastic piping (Napa CRB2672).



Remove the throttle body and take it to the workbench.

Using an oiled tap along with a driver, carefully thread the lower of the 2 holes of the throttle body where the old fitting was plugged in. Don’t go too deep. These are pipe threads.

Flush the hole with carb cleaner and inspect for any left over cuttings.
This is an excellent time to do a complete throttle body and IAC cleaning. See Tip 11.
Take the vacuum fitting (05703-B102 ) and apply a LITTLE bit of thread sealer on the threads only. I prefer Permatex #2 but almost anything is fine.

.

Carefully screw the fitting in until snug.

Install one of the vacuum elbows on the MAP sensor so it points toward the throttle body, and the other vacuum elbow on your new throttle body fitting so it points up to the MAP sensor.
Cut a length of the new plastic tubing (approximately 13 inches) to fit between the vacuum elbows and install it making sure there is enough slack for some engine movement. Route it according to the photo. We don’t want any rubbing or chafing with engine movement. Not a bad idea to use some contact cement or Gasga-Cinch sparingly on the tubing to elbow connectors.

 

I was hoping for a solution that didn't require tapping a hole and removing the throttle body completely.

 

Oh, you mean one that doesn't work well....Keep looking.

 

What other options are there? I thought I read somewhere mentioning you could run the hose to the IAT sensor. What fitting would you need to this? Also how would I close up the bottom hole on the grommet to throttle body?

 

I have provided the most straightforward solution. I actually went to NAPA, purchased the parts, documented them and the procedure.

If removing the throttle body scares you for some reason, I can't help that.
Seems to me it would be a good opportunity to give it a good cleaning and a new gasket.

The BIGGEST issue with the whole set-up is the throttle body hole. Face reality.

 

That is right cause Napa is the place to buy parts. LOL.
Hey the CRB 2-670 elbow.
Would that work on my '00 for the MAP sensor?
I just get them from the dealership but am curious.

 

I don't know.

I'm suffering from PTTBS at the moment.

 

So we ended up getting the existing grommet out of the throttle body and removed the broken piece of hose that was stuck inside of it with a screw. We inserted a small piece of brake line into the grommet to act as our "nipple" and got it back into the throttle body hole (with some extra patience). We attached 3/16 heavy duty vacuum hose to the end of the brake line "nipple" and ran it straight to the map sensor nipple. Used safety wire to ensure the vacuum hose was secure around the brake line nipple. So far so good. First time my Jeep as got 20 MPG in a long time. Also changed the O2 sensor. Runnign and idling smoother than ever. Found a vacuum leak that was causing my idle to be high. Great weekend working on the Jeep to say the least. One day we may take the throttle body off and try your method but for now we are going to see how long this lasts. @cruiser54

 

Nice job.