87 2.9 Won't Get Past 2500 RPM

[1986ranger]

87 2.9 Won't Get Past 2500 RPM - Resolved!

OK, I got a new (to me) 87 2.9 that does not run right but I don't have much history on it. It will not rev up past 2500 RPM. It seems to idle OK. Manifold vacuum is about 17 in Hg at idle. The higher the engine is revved up, the vacuum drops but remains pretty steady. Once you get closer to 2500 RPM it starts to get eradic. Light colored smoke also come out the exhaust when it gets up close to the 2500 RPM limit. Help!

Update: See below.

 

[capridude]

"OK, I got a new (to me) 87 2.9 that does not run right but I don't have much history on it. It will not rev up past 2500 RPM. It seems to idle OK. Manifold vacuum is about 17 in Hg at idle. The higher the engine is revved up, the vacuum drops but remains pretty steady. Once you get closer to 2500 RPM it starts to get eradic. Light colored smoke also come out the exhaust when it gets up close to the 2500 RPM limit. Help!"


Is your coolant level dropping? Is there coolant in the motor oil?

It COULD be that you have a cracked head(s) that are leaking coolant into the exhaust (whitish smoke).
What is your vacuum at WOT? If it is more than 2" then the exhaust could be getting plugged up.
Have you run any codes from the computer?

Cheers, Jeff

 

[IMenriched]

fuel filter been changed??

 

[1986ranger]

I am unsure of coolant consumption just yet. The radiator was a bit low when I got the truck and I filled it up. I have been monitoring it. I can't really drive the truck so it is hard to get much time on it. I have not checked the oil yet but I will do that here soon. I did a cold, cranking, compression test and got about 150 psi on each of the driver side three and about 120-130 psi on each of the passenger side three. I plan to do a warm running compression test tomorrow. Symptoms are the same whether hot or cold. Vacuum at WOT goes too erratic too tell and RPM hangs about 2400. Vacuum steadily drops as RPMs increase however. It is steady for a while. I don't recall exactly, but I think it dipped to about 10 psi before it got to the point where the engine stopped running smoothly. I also get little backfires (pops) out of the intake when it does this. Back pressure right before the cats is 1.5 psi. It could still be a blockage between the cats and motor. I did a KOEO test and got no current codes and only three in memory. The first was 18, for the SPOUT being recently disconnected. One was EGR related (33). The third was for insufficient input for the vehicle speed sensor (29). I am going to do a KOER test here soon.

Both fuel filters have been changed. Fuel pressure test to follow.

 

[grnrngr]

Only takes a second to pull the stick and see if it looks like pancake batter...
or you could sniff the exhaust ( but not too much) to see if it smells like anti-freeze.. but light/white smoke coming from the pipe of a warmed up motor is usually an indicator..

 

[IMenriched]

check out the tech library...thinking that there is vacuum gauge readings and symtoms there... thinnking this is it http://www.therangerstation.com/Magazine/Summer2003/VacuumLeaks.htm

 

[Roowen]

Not to interrupt but, I have the same symptoms as what you have and am working on it right now,(weird),if I figure it out i'll post it back to you here, and i'll keep checking to see if you get it first.(has to be vacuum related,but what do I know)

 

[1986ranger]

Resolved!

I discovered there was no oil pressure and dug in. The pics speak for themselves. Amazing it still ran, and did for quite a while.