Need checklist for lazy engine

mhjo · Aug 26, 2009

I bought back my old love that I sold 5 years ago, but I see now that the car is not as fast as it used to be. As my brother put it: "it feels like I'm towing a trailer". On low rpm tha car is slow, and in high rpm it's not so bad.
However, mpg is very bad.

I have so far changed plugs, wires, ror, cap and coil. Engine was rebuild 2001, and driving season her (in Norway) is pretty short, so milage shouldn't be the issue.

Anyone help me with a checklist?

golf4283 · Aug 26, 2009

Try resetting the timing. That might help you a little bit.

mhjo · Aug 26, 2009

Thanks. I had someone set it at right degree, but it pinged and I had to retard it step wise back to a "no-ping stage"..

jcode68 · Aug 26, 2009

If timing is set properly, I would take it for a good 5-10 mile drive and then pull the plugs and see what they tell you. Could be running lean/rich and require some carb adjustments. I would also look for any vaccum leaks, which will also affect performance.

dbfarr · Aug 27, 2009

+1 for vacuum leaks. If the car sat, the seals will leak.

Especially the intake.

Platonic Solid · Aug 27, 2009

If the timing was set properly, wouldn't that have revealed any vacuum leak issues since you need to use a vacuum gauge to do it right?

bnickel did an excellent job of describing the correct process in this thread: http://www.stangnet.com/mustang-forums/786418-electronic-ignition-id-rough-idle-s.html

68er · Aug 30, 2009

try pouring a strong mix of carburetor cleaner in the tank and driving it around. It may have sat around too much since you owned it last, and built up deposits in the carb. Berryman's b-12 works good, so does marvel mystery oil and others. i tried this on an old impala that i bought, and somewhere on the second tank that stuff dissolved whatever was clogged and it went from dogging along to burning rubber.

1 can treats 20 gallons, i mixed it into 10.

zookeeper · Aug 30, 2009

Sure sounds like ignition to me. Since you say it pinged before you backed it off, I assume the total advance is about right, but how's the curve? Check initial timing with the advance unplugged, then re-connect it and slowly rev the engine to about 2500 while keeping the timing light on it. All the advance should be in by 2500 rpm's and you should be able to get 34 degrees total out of it. If not, start checking things out to see what's wrong. If you cannot get enough timing in it without the ping, I suspect it has carbon buildup in the cylinders. Carbon buildup will cause pinging, even with very little ignitiong timing.

Rusty67 · Aug 31, 2009

Check the parking brake and the adjustment of the drums all the way around to make sure you aren't geting major brake drag. If someone set it up wrong it would really slow you down.

A compression test wouldn't hurt either.

mhjo · Sep 1, 2009

Thanks for replies!

Car is in for service now, and I received a call today that the electric choke was faulty, and was constantly engaged. They are still working on it, and I will report the findings.

Yes, I will use carb cleaner etc. when I get it back.

mhjo · Sep 2, 2009

And the mechanic said today that when the faulty choke was engaged, it also blocked the two extra intakes in the carb, wich explaines the lazy engine.

Now the car runs normal!

Need checklist for lazy engine

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