papapayne

Fourth 3rd gen and it seems to get 1/4 the gas mileage of my others even though engine is smaller. I seem to get roughly ten or so MPG. I know there is no way that can be right considering I am mostly stock. What problems could cause that?

84 z28 HO 4 barrel.

acadburn

id start by checking your timing air filter and your trouble codes to see if your running rich or lean

papapayne

new air filter 15 degrees at with 4 pin connected no trouble codes

chads89ta

iTrader: (6)

try using some seafoam it should help, also try using a scanner to watch the how slow or fast the o2 reacts to changes

five7kid

iTrader: (14)

Your timing is way off. Disconnect the 4-wire connector and set the timing a 6 degrees BTDC at idle. Then reconnect the 4-wire connector. You can see what it's doing connected to make sure the ECM is controlling the thing, but the actual reading you get is pretty irrelevant.

chads89ta

iTrader: (6)

i sure missed that one, it flew right by me . yes the base timing has to be done this way. that should help

papapayne

adjusted base timing to specs...it was 19 degrees...so higher then advanced. but no dang codes!!! I don't get it. i fixed the timing but still getting crappy milage. car runs lean.

Kevin84Z28

iTrader: (3)

If you're running the CCC Quadrajet E4ME then your TPS is probably bad. You'll need to run a simple diagnostic on it and see whats going on with it. I won't pretend I know what I'm talking about but I've experienced the same problem and that's what was wrong. The ECM controls the amount of fuel to feed the carb based on information gained by the TPS. I think the values are similar to 1.0v at idle to 5.0v at WOT. If the TPS is broken and reports 5.0v then the computer continusly runs rich. The results are poor running at low speeds, better at high speeds but poor MPG all around. You'll need a digital dwell meter to check it.

five7kid

iTrader: (14)

That's not "to specs". I already told you what "to spec" is - set it that way.

Running lean and getting crappy gas mileage doesn't compute.

If the TPS was causing the problem, it would be setting a code.

Is your SES light bulb burnt out?

papapayne

u said unplug four pin to the distrubutor and set base timing correct? Thats what I did. well, thats what the shop did I had them tune the carb and part of that was timing.

five7kid

iTrader: (14)

Okay, what you originally said was hard to understand exactly what you meant.

papapayne

yea sorry about that. I really need to get my buddies scanner and dwell meter so I can put some info up for you guys.