Surging/Bucking at 2800 rpm - accelerates perfect

[CLJustin407]

Hi all and Happy New Year!

2003 Ranger Edge 2WD V6 3.0L Manual Non Flex

I have just done a engine swap (1st time doing any engine work) and have everything up and running great (just like a new truck). One more problem remains that followed me from before the swap. I have a surge/buck that happens at around 2800rpm in any gear (manual trans), It revs perfect when in neutral or clutch engaged as well. Sometimes I can push through it and continues on without problem. I thought this was initially an issue with the bad engine I pulled but it seems that it is still around. I will list what has been done below:

- New (used) 3.0 put in (runs great, no CEL)
- New clutch/flywheel
- New fuel pump assembly/filter
- New camshaft sync shaft (in back of motor w/oil pump drive)
- New crack sensor (on balancer, front of motor)
- New trans fluid (from dropping it for clutch and flywheel)

Basically new everything. It has great acceleration but only bucks and surges when I hit around 2800 rpm in each gear before I shift. On the highway I can't get over 60 due to the rpm's.
It is only rpm related and nothing to do with what speed I am going in each gear. I have spent a great deal of time searching for this problem but any other related issues people complain about involve not having acceleration, this is not the case here.

I appreciate any help, this site was invaluable along with youtube to get the thing back on the road.

 

[91stranger]

Any history on the transmission? Mileage? Fluid color?

 

[CLJustin407]

the truck has 221k on it, assuming its the original. fluid is pink, I changed it with fresh when I dropped it to originally change the flywheel. Like mentioned it runs great besides it surging and bucking at around 2800rpm.

 

[91stranger]

Will it continue to surge and buck if you hold it at 2800 rpms? What happens when you let off the throttle when it happens? What happens when you mash the pedal when it happens? Is it a hard buck where it spills your drink or just annoying like hitting a pothole or something? You say this does it in every gear at 2800 rpms? Sounds pretty strange but I would suspect the transmission since you swapped the engine and you had this issue prior to the engine swap. Have you checked rear end or changed the diff fluid?

 

[Dirtman]

Is it possible the truck is haunted?

 

[CLJustin407]

It will sometimes push past the surge and continue accelerating fine. When I let off, as soon as the rpm drops it stops. When I peg the trotlle it does exactly as it should provided its not near that rpm. I would say between spilling drink and annoying. It hasnt done this always, even before the swap I was able to drive it fine. I want to say it happened after the trans was pulled, but not sure. In any sort, I made sure everything was put back correctly. I just cant seem to shake this problem. If it wasnt for the surge/buck, you would never know there was anything ever wrong.

 

[Rearanger]

TPS dead spot?

 

[RonD]

My GUESS as well, TPS(throttle position sensor), but also Coil Pack, look for cracks, there are 3 coils in the pack, if one was misfiring under load then it would be a stumble, but I would expect a Flashing CEL for that, but I would also expect a code and CEL for TPS

Its like the computer doesn't know the engine is stumbling, which is not all that odd but.................

You could invest in a Bluetooth OBD2 reader(under$40) works on any vehicle sold after 1996, and with any smart phone, apps are free or $5
Then watch Live Data during the stumble, i.e. TPS voltage(%) for a sudden drop, or spark advance

 

[CLJustin407]

New coil pack installed amd new tps as well. Pretty much every sensor was changed before engine swap, kept all original harnesses and electronics during the swap.

No CEL

I feel kike its the rev limiter, but its a manual and as far as i can tell that should not be a problem. It revs past 3k in neutral, it has a very slight limit right at 2800-3000 in neutral though, but quickly goes away when given gas. I k nm ow the truck drives normal it did before even with the other engine going out, i just remember being in the highway randomly one day and the problem started.

 

[RonD]

Unplug the Cam Sensor
See if engine will start, some 3.0ls won't run without it, some will, it depends on the software version

If it starts then drive it and see if the glitch is still there

 

[CLJustin407]

Will try unplugging, also just checked the cel bulb and it was out, changed it and it does have CEL on while running. I am going to order a bluetooth odb2 reader amd get codes in the next day or 2 amd will revisit after. Thanks so far everyone.

 

[RonD]

Yes, codes may help, but might just be EVAP code, lol

 

[Dirtman]

Rev limiter is 3k at idle. Way more in drive.