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Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 22918
Experience:  BEng hons Mech engineering, in auto industry 22 years
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transit mk6 ticks over ok but will not rev up at all, I have

Customer Question

transit mk6 ticks over ok but will not rev up at all, I have replaced the throttle unit nothing changed! Starts clean and ticks over.Had OBD unit on it but the message was "failed to link" this happened on two different readers!
Submitted: 4 years ago.
Category: Car
Expert:  Matt replied 4 years ago.

if there's a communication error with the OBD reader then this could well be a wiring fault on the ECU or an internal fault with the ECU

I'd suggest checking over the state of the pins in the ECU connector plug for any corrosion or damage and also check that all the engine ECU fuses are in good condition and not cracked or corroded

if this all looks ok then I'd consider sending the ECU off for repair / testing

I can reccommend both of these firms
Customer: replied 4 years ago.

the engine failed while it was being driven, pulling good then no pull only tick over rev 800rpm had to limp home useing only the 800revs that was challenging

Expert:  Matt replied 4 years ago.
Hello Neal

Ok thanks for the extra information

my original advice is still valid

but I'd also check for a wiring issue as things tend to expand when hot and its possible a poor or partial electrical connection is being pushed apart on one of the major sensors so check the connection plug and wiring to the following;
Airflow meter
Crank position sensor
Cam position sensor
O2 sensor
Throttle pedal position sensor

Also worth checking the connections to the fuel pump for the same reason - unplug each in turn and give them a good squirt of switch / contact cleaner - Not WD40

and also unplug and inspect the main power relays and fuses for signs of overheating or corroded terminals - so the ones for the ECU and the fuel pump

And also unplug the wiring loom connections in the engine bay one at time and inspect for corroded or recessed pins.