3.4 swap into 1985 Jeep Cherokee questions?

[Canyonero]

That could be the lack of VSS. I found a vacuum leak that was keeping my idle high at the same time I connected my VSS. I idle way lower now, and it does dip when I clutch, but not to the point where it stumbles or dies. My Trooper idles about 600RPM normally. I would disconnect my VSS and see what happens, but that's too much work. :P

[cardana24]

That could be the lack of VSS. I found a vacuum leak that was keeping my idle high at the same time I connected my VSS. I idle way lower now, and it does dip when I clutch, but not to the point where it stumbles or dies. My Trooper idles about 600RPM normally. I would disconnect my VSS and see what happens, but that's too much work. :P

My warm idle is steady at 700 rmp. So why would my engine die when pushing the clutch in when coming to a stop? When the engine is cold it works just fine....so would that point to a VSS? I posted this on a V6 camaro board but I have not gotten any replies yet...so what would cause it to die?

[Canyonero]

You might want to start new threads for specific issues, more people might chime in that way.

[ssterlingb]

I saw something about the VSS causing what you are describing, but I can't find it now. If I am remembering correctly, it said that the ecm runs the emissions with the VSS telling it when to open & close the EGR, canister purge valve & stuff at highway speeds. The computer keeps all of that off while the engine is warming up, so it uses the temp sensor as well. I think it said that it needed the break or clutch switch to disengage the transmission stuff & the VSS to control the vacuum, so if the VSS was bad, it would cause it to stall or near stall when stopping.
I'm pretty sure I remember that part correctly, but I would feel better if I could find that thread again to verify. Maybe that will help though..

[cardana24]

I saw something about the VSS causing what you are describing, but I can't find it now. If I am remembering correctly, it said that the ecm runs the emissions with the VSS telling it when to open & close the EGR, canister purge valve & stuff at highway speeds. The computer keeps all of that off while the engine is warming up, so it uses the temp sensor as well. I think it said that it needed the break or clutch switch to disengage the transmission stuff & the VSS to control the vacuum, so if the VSS was bad, it would cause it to stall or near stall when stopping.
I'm pretty sure I remember that part correctly, but I would feel better if I could find that thread again to verify. Maybe that will help though..

I'll try starting a new thread on this. Do you know if our jeeps have a VSS built in? I am guessing not since that is cable driven. If not I will go ahead and order one of the ones that Canyon posted a link to.

[cardana24]

It's used for emissions and fuel trim calculations. You can drive without it, but you'll get a CEL. I just hooked up mine after a year, still don't know if it's working right (still get a CEL). I had a VSS already, built into my speedometer.

You can get a VSS that plugs into the transmission before your speedometer cable.

http://www.jagsthatrun.com/Pages/Spe...eedometer.html

So will this^^ work for my jeep? The speedo is cable driven, I don't want to loose my speedo by doing this?

From reading more about the VSS, that seems to be my problem.

[ssterlingb]

I'm not sure, I remember that the post I read about it in was discussing moving Chevy fuel injection engines into off road aplications. It was talking about the new v8 engines mostly, but talked about how the GM fuel injection had to have a couple more sensors to work properly & I remember it saying that the ecm adjusted fuel mixture depending upon speed, temperature, & emissions. So if they were trying to remove the emissions, or not using some sensors, they had to try & reprogram the ecm, but it was easier just to use the motors 'as is'. I remember thinking I should be okay on my conversion since I am also replacing the transmission with the 4L60E, thats why I remember the VSS being a potential problem.

[cardana24]

I still don't know what adaptor to use for the VSS. There is one listed to fit the 3.4 engine, but it was never mated to an AX5 from the factory. The one that is listed has having a hook up for a speedometer cable looks like a possibility but it's list as fitting early 90 crown vic police cars, since the cable output was used for radar. Also with the cable fitting I am not sure how to attach the cable to it since mine is made to be held down with a screwed down tab. It looks like the one in the picture is made to have the cable screwed down to it.

I would love some help but those guys do not answer the phone and I do not see a clear answer on their infomation provided.

[cardana24]

I may have found someone that can help me. I need to know if the signal is a Hall effect signal, an A/C (alternating current) siginal, or a D/C (Direct Current) signal.

From reading on the Stealth conversion/jags that run site, it it says that the camaros from 91-93 are A/C....well my engine came out of a 94 camaro.

Can someone please varify which signal I need. Thanks.

[cardana24]

So I painted the jeep this weekend, and I was going to back it out of the garage to get everything cleaned up, and when I put it into gear it did not go anywhere. None of the forward gears are working nor reverse. What in the world would cause this? The only thing I have done is put a shift knob on the jeep since last time I drove it. I drove it into the garage, and now about a week later it will not move when in gear. Any help?

[Canyonero]

Your transfer case is in neutral.

[cardana24]

Your transfer case is in neutral.

good call, I did have to move that when putting the console back in. Thanks for the idea. I hope you are right!

[Canyonero]

Basic troubleshooting technique. Check the simplest things first, and double check anything you touched in any way since it was working last.

[cardana24]

Basic troubleshooting technique. Check the simplest things first, and double check anything you touched in any way since it was working last.

I agree, you just need another set of eyes/opinion some times. You are right, it was the T/C in neutral. It's shifting fine now. Thanks.

[cardana24]

The VSS that I got from Nevada Speedometer did the trick! I am now using my cable driven speedometer and I also have an electronic output for the ecm. Now when I clutch the jeep on deceleration it does not die! I took pictures that I will upload soon I have just been super busy.