I'm the new guy needing some help. Picked up a 84 244 with 167K. The guy i bought if from said it had gremlins and it does! Starts great always, but sometimes it just won't accelerate above 40 mph and just no power. I just pull over, turn it off, start it right back up and it runs fine, 70 mph for 10 miles to work, all good. It's done this for months now. What I've replaced: MAS, fuel PR, in tank pump, and filter, in tank and main. I've not replaced the main fuel pump yet, but i have replaced both relays. Also, when i replaced the fuel filter, it had what looked like black pepper coming out of the input side.

When it's running good, it runs and idles fine, but at least once a day, it just refuses to go over 40! and pushing the accelerator makes the engine just bog out.

Any thoughts?

Many thanks

Thanks, I'll try removing the o2 plug over the weekend. And you are right about the wiring, at that gray 8 pin it is really really bad on the engine side coming out and by the coil i have 1/2 in or so of bare wire.

I can't go for a new harness at the moment, but can i start to replace the wires one by one from the gray 8 pin and under the engine, where ever they go? I could get individual wires from Dave B. If i were to start replacing from the gray 8 pin as it passed under the intake, what components will in end up at? I have a Bently but having some trouble following the wires final destination.

Many thanks

the important wires are the 1s that run from the engine to the ecu. injectors, sensors, etc. the red, black, yellow, etc on the firewall don't affect running. good luck, chuck.

I had troubles like this and found it to be the main pump. I mean, it ran, albeit noisily, but I could tell it was failing by how throttle response would fluctuate. There was no rhyme nor reason to the fluctuations either. Sometimes, kickdown into third would take just a small prod to the accelerator pedal, and at other times it would take far more. Finally one day it just boggged down when asking it to accelerate briskly. Turns out the main pump was having trouble moving the volume of fuel needed to sustain an acceleration or cruise at speed.

Main pump replaced and the car has throttle response like I haven't felt in over a year. Obviously, the failure was a slow degradation.

If you do discern the problem to lie with the fuel pump, get a proper Bosch pump. You won't regret it. Check first to be sure someone hasn't hacked out the factory terminals though. I am still dealing with the fact that my car had altered wiring.

Good luck.

look at the harness at the temp sensor. if it's a new design, there's a red sleeve on it with pn 3515397. if not, then look for flaking insulation and maybe a new design harness.

look at the fuel pressure. does it stay at 40-45 psi when this happens?

remove the o2 sensor from the manifold. if the cat is clogged, this acts as a bypass for the exhaust. if it runs always better this way, needs a cat and maybe exhaust. those cat chunks don't dissolve. good luck, chuck

Sounds like you have a failing AMM. If it not doing its thing, all the time the car limps!

I would want to blame the wiring harness on this year car!

You may have to cut open places in the sheath and see where it has "biodegraded" insulation.

I like blaming engine cleaner that lays behind in the harness and cooks off but all the 83's to 87's cars suffered some issues.
Usually happen under the intake manifold and up to the firewall as the first place that goes!

It can also be the connector pins on the AMM. They can become corroded or are pushed back up inside the connector as they can get sprung.

Hope this helped?

Phil

Engine cant breathe. Sure sounds like a clogged/bad cat and or exhaust system.