Aidan Posted April 28, 2020 Share Posted April 28, 2020 My tach reads less than 500/nothing. I can't figure out how to adjust the rpms so the read right (they don't have to be perfect just close ) Just replaced dummy lights and sensors Sent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
Aidan Posted April 28, 2020 Author Share Posted April 28, 2020 Maybe I'm crazy lol does this look right for warm idle? It seems to be sitting below 500 the warmer it gets Sent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
fiatslug87 Posted April 28, 2020 Share Posted April 28, 2020 Does it sound like it should be higher than that? Ideal is ~700 RPM I think. if your tach is adjustable this might help. Link to comment Share on other sites More sharing options...
Minuit Posted April 28, 2020 Share Posted April 28, 2020 It's lower than it should be, but considering a Renix 4.0 in need of maintenance can have a pretty shifty idle I can believe it. Don't adjust it before you know for damn sure it's incorrect. Do you have a scan tool for your truck? Can you post a video of what your engine sounds like idling? Link to comment Share on other sites More sharing options...
Aidan Posted April 28, 2020 Author Share Posted April 28, 2020 I think I'm not understanding where exactly the screw to adjust the tach is. Is it INSIDE the tach itself or on the back??Sent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
fiatslug87 Posted April 28, 2020 Share Posted April 28, 2020 It's on the back of the tach itself, you have to get it out of the case. Those screws in the picture are what attach it to the circuit board at the back of the case. But follow Minuit's advice first. Link to comment Share on other sites More sharing options...
Aidan Posted April 28, 2020 Author Share Posted April 28, 2020 I have an OBD2 scan tool but I didn't think you could even plug them in on these trucks? And I tried but apparently I can't post a video Sent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
Aidan Posted April 28, 2020 Author Share Posted April 28, 2020 How do I remove the potentiometer for adjustment? I've been looking on all the Jeep forums and all the pics that come up are "removed" or somethingSent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
Aidan Posted April 28, 2020 Author Share Posted April 28, 2020 Or even just drill a hole to access the adjustment screw lolSent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
JustEmptyEveryPocket Posted April 28, 2020 Share Posted April 28, 2020 52 minutes ago, Minuit said: It's lower than it should be, but considering a Renix 4.0 in need of maintenance can have a pretty shifty idle I can believe it. Don't adjust it before you know for damn sure it's incorrect. Please re-read this comment. Then read it again. And again. Then ask yourself if you really need to adjust the tach. . . I would recommend that you start checking grounds, sensor values, connectors for green crusties, gunk in connectors, etc etc. Go through all the main cruiser54.com tips. Your tach is most likely reading correctly and needs no adjustment. Run through all the other likely sources first at least. Link to comment Share on other sites More sharing options...
Aidan Posted April 28, 2020 Author Share Posted April 28, 2020 I did all the ground cleanings from cruisers tips already and even did the c101 elimination. I was honestly just concerned (from the other manual vehicles I've owned) that the RPMs were too low. If you saw the pictures and think that is where it should be then I'll just leave it alone and enjoy my new cluster it idles just fine i just thought the cluster I purchased was from a 2.5 (mine is a 4.0) and needed to be adjusted Sent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
JustEmptyEveryPocket Posted April 28, 2020 Share Posted April 28, 2020 Well, run it through an RPM range. Does it respond like it should? The 2.5L to 4.0L might be a valid concern. Link to comment Share on other sites More sharing options...
Aidan Posted April 28, 2020 Author Share Posted April 28, 2020 It seems REALLY low to me. At idle when warm it sits at about 250/300 RPMs. And when I step on the gas the RPMs don't go nearly as high as it sounds. At 3500 it sounds like I'm redlining the hell out of it Sent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
Eagle Posted April 28, 2020 Share Posted April 28, 2020 1 hour ago, Aidan said: Maybe I'm crazy lol does this look right for warm idle? It seems to be sitting below 500 the warmer it gets Sent from my moto e5 play using Tapatalk You're reading it wrong. That's indicating approximately 700 RPM. Note that the tach scale is linear -- all the way around, the divisions are the same size. BUT ... at the bottom end of the scale, they left off the tick for 250. No need for it, because the engine never runs at 250 RPM. Link to comment Share on other sites More sharing options...
Aidan Posted April 28, 2020 Author Share Posted April 28, 2020 OHHH okay that makes me feel a lot better lol. Thank you everyone for your responses!! (And sorry for all the dumb questions)Sent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
SoCalManche Posted June 7, 2020 Share Posted June 7, 2020 Reviving this thread for a question that also deals with calibration. I have an '86 2.5L and I bought the truck with a busted tachometer, where idle would read 4,500-5,500 RPMs, and when you're cruising down the highway, the need is pointing direction at 6 o'clock. I like the red clusters anyways, so I snagged a full cluster to swap in and be done with it. Well, the tachometer is playing silly again, and now I'm reading 0 RPMs, even though it is calibrated to 4 cyl. And I'm very sure it is calibrated to the 4 cyl because if the adjuster is rotated the other way entirely, idle reads below the 0 RPM mark, even though it responds quickly anytime I open the throttle; the other tachometer also responded appropriately when throttle opened up. So my question is whether or not I'm extremely unlucky and both tachometers are just botched? I tested for voltage at the ICM and the dash harness, and got battery voltage both times, as well as 0 ohms as well. Any thoughts? Link to comment Share on other sites More sharing options...
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