Thread: 98 D1 V8 bad fuel economy - 43.2L per 100km - vacuum advance?

What happened can you let us know.

Paul

Some significant improvements:
21L per 100km driving around
24L per 100km towing a 1.5t boat and passengers on the highway.

Vehicle gets up to operating temperature now.

Of note is that the exhaust pipe to the main muffler have seperated so might be having an effect until repaired.

Havnt checked the temperature sensor resistance (Ohms) yet, still need to figure out where it is located on the engine.

Also haven’t checked out the MAF voltage or adjust the screw adjustment on it. Wasn’t sure how to get the voltage reading from it - need to break the insulation on the wiring to get a multimeter probe I guess?

So maybe some further gains to be had?

Originally Posted by twr7cx

Some significant improvements:
21L per 100km driving around
24L per 100km towing a 1.5t boat and passengers on the highway.

Vehicle gets up to operating temperature now.

Of note is that the exhaust pipe to the main muffler have seperated so might be having an effect until repaired.

Havnt checked the temperature sensor resistance (Ohms) yet, still need to figure out where it is located on the engine.

Also haven’t checked out the MAF voltage or adjust the screw adjustment on it. Wasn’t sure how to get the voltage reading from it - need to break the insulation on the wiring to get a multimeter probe I guess?

So maybe some further gains to be had?

ECU temp sender is really easy to find, look at the inlet manifold just behind the top radiator hose, there will be a vertical two wire plug on a sender that's screwed into the front water passage between the passenger side head and the back of the thermostat.

MAF readings require you to pull back the rubber boot off the connector plug, terminals are then easy to access with a pointed probe.

Thanks. I'll try and get onto both this weekend. Have had only very limit short opportunities to look at it so far.

JC checked the MAF reading for me the other day all good. Advised that the temp sensor should be fine too as he checked it previously and the temperature gauge is working fine.

Car doesn't love short trips - drinks a lot for these. But longer journeys and towing it's reasonable.

I will say that the Rover V8 is one of the nicest sounding V8's. I've had a few Ford Windsors and Clevelands previously but the Rover V8 seems to even sound great with the stock standard tiny straw of an exhaust.

They do drink when cold, the cold enrichment is one of the issues and you can't really avoid that. Having a new thermostat helps the engine warm up quickly though. I'm currently doing a few jobs on a D1 V8 to get it to run better on petrol (and LPG) and the number of small things I've found definitely add up. TPS was buggered, the fuel pressure reg had been hooked up to the wrong port, the plugs and leads were stuffed, the vacuum advance was stuffed, timing was wrong etc. The previous "technician" had just replaced the MAF at vast expense, the old one turned out to be perfectly fine and went back on. In the end though there is a price to be paid for the sound of a low compression LRV8 being stoked into song and that's expected.

JC checked the MAF reading for me the other day all good. Advised that the temp sensor should be fine too as he checked it previously and the temperature gauge is working fine.

The temperature gauge has a different sender to the ECU sensor.
The ECU sensor tells the ECU what it thinks the engine temperature is.
If too much resistance then cold enrichment.
Regards Philip A

As Philip said, check the sensor, the gauge means nothing to the ecu. Check the actual running temp with a known good gauge if you can, not the gauge on the dash. Economy can change dramatically between 70 and 85 deg running temps....