Looking for any suggestions. I have a 1997 Discovery I. It went down a month or so ago and I took it into my mechanic who does own and have some experience with a Discovery 1. Initially the ignition was replaced as well as a cam sensor that was throwing a code. The fuel pressure was not good and a new fuel pump was installed. The issue now is that it will not go above 2800 rpms. It starts and takes off with no issues, but the second it hits 2800 rpm or so, it just stops accelerating and does not shift. My mechanic says he has checked out everything he can think of and is completely out of ideas. Has anyone else encountered this or have any ideas?

 

Clogged cats can do that.

 

Yeah it sounds like an air flow issue, either in our out. Exhaust not making its way back or vacuum lines clogged on the front.

If you are sitting in neutral, will it rev past 2800?

 

I haven't tried it in neutral. He did say they checked for exhaust clogging and there was none.

 

Just got it back from the shop. It will not go above 2500 or so RPMs in N or 3, 2,1. It seems to run fine until you get up to that RPM level. It has new ignition and fuel pump. According to the mechanic, there is no issues with exhaust clogging. What would anyone suggest to start with?

 

How did they verify the exhaust isn't clogged up? Did they loosen the Y pipes at the exhaust manifolds? Just because some exhaust comes out at idle does not mean it's not clogging up at higher RPM's. The fact it won't idle past 2500-2800RPM in N points to something restricting the airflow into the engine or flow out of the engine. If it was transmission related it would only do it in gear. Did they verify fuel pump PSI at the rail? Should be in the 30PSI range. Is the throttle cable assembly free and not binding?

 

So I asked how they verified the exhaust wasn't clogged and they said they removed the O2 sensors and it didn't change.

Throttle cable moves fine and is without binding.

 

I sure hope they removed the ones in the front of the cats vs behind as that would be null and void lol.

Fuel Pump
Fuel Pressure Regulator
Clogged Fuel Rail (I've seen a few in my day and they were GROSS)
Clogged Intake/Air Filter
Clogged Exhaust/Cats
MAF
Vehicle Speed Sensor (did the speedo ever bounce or stop??) If the VSS is bad it can think you're going 110MPH and basically govern the engine. Cheap Chinese units are pure crap. There is a write up on how to take it apart and clean it.

Only other wild thing I can think of is a badly corroded ECU under the hood. However normally you'd have some funky acting things, but as with any electronics they can all have a mind of their own. You can simply check the connectors for corrosion and remove the ECU and remove the sides to look for corrosion. If it looks good = probably not your problem as the GEMS ECU's are very robust with the exception of corrosion.

 

Unplug the MAF, see if it will rev.

Do you get any backfire/popping?

 

Could be the VSS, mine did something similar to that when it was acting up.