Outer Limits 4x4 Board

My 88 rangie motor was stroked to a 4.2 before i bought it, but now at idle it surges, what could be the problem. Another problem it has is that when it is cold it idles fine, but then when i press the accelerator it nearly dies and generally runs like a dog.

My 87 did this pre-engine transplant. I discovered that the pipe on the fuel regulator had been adrift, maybe causing this I also did an engine swap recently with a complete loom and ECU and removed the old one and now nop more problems

Is your Rangie running std L-ject 'flapper' EFI or has it been upgraded?

Trav

I dunno what efi it is running, but i know it has a Motec computer box thingy under the seat. How do i check, because unlike my other rangie it only has a ring in the air intake, not the box AFM.

Ah, that would be a motec ecu, so there is no afm. Sounds like you need some tuning or maybe the vac hose to the ecu has a leak ?

Ran across something like this a few months ago.
Does it surge if you put your foot on the brake.
One of my club members has a Motec on a 4.6 and found that in low range while braking the engine revs surged.
Dunno the reaon but My theory is that the brake changes the vacuum and the ECU thinks the load is more therefore gives more fuel.
So could be a vacuum leak or something to do with one of the internal settings of the ECU. They have adjustable enrichment rate etc.
You are probably up for a dyno session.
Regard s Philip A