Just got my tachometer back from Isspro for warranty work. I havent had it in since the PODs went in. Sure seems like the road speed is alot higher than it should be at a given RPM. ??? 3.55 rears, Getrag 5spd, at 70mph I am at 1850-1900 RPM. At 85mph I am at 2400 RPM. Is this about what you guys are seeing with a 5spd manual and the PODs? I dont know if the bigger injectors would make a difference or not, but, it sure seems like the RPMs are lower compared to the speed I am traveling.<br><br>

 

I don't have a manual trans, but.......

Swapping injectors should not have this effect. Since the speedo signal is taken from the driveshaft speed, I'd bet it has something to do with when the tach was serviced maybe it was re calibrated. Either that or your clutch is slipping :'( How much has the engine speed changed?

Sean

 

When I was running a Getrag the 70mph rpm's were about 1800 to 1900 with 3.54's. I couldn't stand the tranny noise at 2400 rpm's so I didn't run that fast. ;D ;D ;D<br><br>Bob

 

Humm...just whipped out the calculator.....<br><br>Based on your readings at 70mph,<br>1850rpm @ 70mph = 2250rpm @ 85mph<br>1900rpm @ 70mph = 2310rpm @ 85mph<br><br>The ratio should remain fixed, unless....well, you know :<br><br>Sean

 

Thanks for the replys fellas. I double checked my readings today. The numbers are more like 2k at 70 and so on. Dont know why they were so off yesterday. ???

 

Monty, I don't know if this'll help, but mine today at 60mph was running about 1650-1700 and 70 mph 1900 rpm, but it was flat level ground and no real wind. Installed the Isspro tach last week, they say it'll work with the crank sensor, but not on mine, had to order the magnet kit, raised the sensor to &quot;CLEAR&quot; the magnets and A/C quit working, lowered it to just .020 from magnets, A/C works, and 3-4 &amp; 4-3 shift problems gone away????????????????????????????????, shifts out to 4th at 52 mph even at lead foot, and keeps climbing.

 

Thanks for the numbers pumpdaddy. A/C quit working? shifting problems gone.... whoa thats weird

 

Monty I was wondering are you saying you get different readings on different days? If you are you are not alone. I just thought I was crazy at first but I have noticed a difference but no pattern. Seems to be about 100-150 rpm difference. Ive got a Banks gauge but its made by isspro. :

 

Yessir, I do get different readings sometimes, but not always. Like you said, most readings are off 150rpm or so.

 

Humm.....does this fluctuation happen more when the engine is stone cold below a particular temp?<br><br>Sean

 

Eww. I hate to anwser this question becuase my problem will probably point towards a weakining injector pump. :-[ Just this morning after starting, I noticed that the truck was idling at 875-900 compared to the 800 rpm that it is set at. Seems like after the truck is warmed up and up at operating temp, it idles like it should.