rpm at highway speeds

[BigSwede]

FWIW (not much) my Trooper, with manual transmission, 35" tires, and 5.38 gears is turning around 3300 rpm at 75 mph. But here is the point - I still get 15-16 mpg at that speed on a lifted vehicle that was only rated for 17 highway by the EPA in stock form. And these DOHC engines aren't strained in the least by running that high of an rpm all day.

So I don't worry about it.

[mindaugas]

And these DOHC engines aren't strained in the least by running that high of an rpm all day

that's cuz yer trooper is a trooper

I stripped the bolt trying to get the cover off the FPR, might try to find some more alan wrenches or something, or have a shop do it. not looking forward to trying to get the rear one off.

[subject47]

I just finished a trip this past weekend 2600 rpm speedo read 66 mph but i was doing 70 verified via gps on 32" tires

[vt_maverick]

2600 RPM at 70-ish for me, although it varies based on whether you're going even slightly uphill or downhill and obviously when you're coasting vs. accelerating to keep 70. Regardless, with Kilby plates, oversize tires, heavier rims, cargo basket, and roof mounted spare I still got 17 MPG in mostly interstate driving through the mountains.

[mindaugas]

Gonna take it to a shop here in a bit to try and get that FPR out. I can't get past the first bolt I stripped.

[mindaugas]

Fuel pressure regulator and exhaust gas regulator both replaced, STILL high RPM at 70mph. AND, this is going down a f'n hill ... I tried with power off and on, and AC off and on, always the same RPM at 70mph. At least it's consistent.



In other news, the FPR and EGR fixed the start problem I was having.

[PK]

Some points to consider -
1. Did you try the overdrive test suggested by Mark in post #4?? Or count your gearshifts as you accelerate?? If you are not getting into 4th gear, that would account for about the difference you are experiencing. Your transmission selector might be out of adjustment, and you are driving around in 3rd all the time.
2. Is your transmission slipping?? That will account for higher revs, but only going uphill.
3. Do you know the vehicle history?? Previous owner might have changed the diff ratios if they were running bigger tyres at some point.
4. Do you have a Scangauge or similar, that you can test your RPM with?? Tacho in dash might be giving a false reading.

This is definitely not an engine problem.
It is a transmission, gearing, or tacho problem.

PK

[mindaugas]

Did you try the overdrive test suggested by Mark in post #4??

I did, sorry. I tested at 60 and 70, and both times 3rd jumped the RPM by about 1k. So it's definitely getting into OD.

2. No tranny slip at all.

3. I do not know the full history, but I doubt it ever had big tires. I really liked this one because it looked stock.

4. Nope, and although the motor isn't very loud, it feels like higher RPM simply through throttle control.

In other news, the FPR and EGR made it more responsive and generally drive better through the city. I also have 0 startup problems now.

[p_justin13]

I'm on stock size and commute interstate every day. 70-80 hovers right between 2500-3000 at all times for me and I'm still getting close to 19 MPG in the summer heat usually only 14-17 In winter

[mindaugas]

80 in a VX?

[Ldub]

Recent long distance testing between Fgo & Hampton SC indicate 2250 rpm @ 70 mph...35" tires.