Why is my car running so rich? C900

Question

My car - 1984 T16 - appears to be running rich. The plugs are very sooty, and at most I seem to get abour 60 miles out of £10 of petrol, way worse than my previous T16. I usually got around 90 or 100 miles from that out of £10 (12.5 litres, standard 95 ron U/L)

So far, I've set the timing correctly. I've fitted new filters changed the oil, and replaced the plugs (NGK BCP7EX). I've cleaned the throttle body, reset the idle speed and flushed the intercooler. I've also cleaned (with brake cleaner) the AMM and reset it back to 380Ohms as stated by Haynes. The car runs a lot better, but it's still uneconomical. Even when I stay off the boost :-(

Any ideas? I've checked for fuel leaks, both without and with the engine running and I can't see any at all.

Thanks for any advice!

Mike

hippo · Accepted Answer

Checked compression? dodgy leads? timing? (actually right and not justshowing right but slipped one or more notches), or an over enthusiasticcold start valve? Otherwise no ideas, but good luck!

Chris · Answer

I never got better than 27mpg mixed on most of my saabs, (about 70 miles on a tenner). including an 8 valve carb, injection and 16V turbo

Probably the way I drive :-) - but that doesn't explain why I'm getting

35mpg on an old 2.0 sierra....

Could be the FPR valve, check for fuel smell from the vacuum hose. Also the AMM could still be faulty - don't think the '84 has a check engine light?

MeatballTurbo · Answer

In article ,      spouted forth into Are you sure about those plugs?I'm sure it should be BCP7EV, or was the EX just a typo?Can you smell any unburnt petrol coming through the exhaust, and is the exhaust sooting up at all?How about paying a Garage a few quid to check the emissions few you to give you a clue as to where things are going wrong?

chris · Answer

Well it could be a leaky hose(valve cover breather tingy),  but, my best guess is the idle valve.  Butdont forget the olde "go" juce has gone up a bit since GWB and teflon Tonygot in the act.- - another Chris.

KeithG · Answer

Setting the AMM to 380 is not the correct procedure. Read the o2 sensor and set the AMM according to its response to get an average of 0.5V at the o2 sensor. If it is dead, or the fuse blown, or not connected, this could cause your problem. Check these next.

KeithG

Mike P wrote:

Mike P · Answer

According to the Haynes Manual it is the correct procedure. I don't have an 02 sensor either. It's a 1984 C900 T16, which in the UK means it doesn't need a cat.

Anyway, I cleaned the AIC out, seems to have solved the problem and the car is much smoother to drive in traffic. No visible fumes out the tailpipe, and it picks up well.

Mike

Why is my car running so rich? C900

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