Cold weather Mechanics

[tgranthamfd 29]

Just wondering if any of you guys up north, where it is really cold, have any advice for a problem I am having? My daily driver is a 1988 Jimmy 4wd (full size) with a 5.7 V8, and a automatic transmission. The problem I am having is, I loose power when it is really cold out, which has been a lot here lately. Between 30 and 55 mph, service engine light comes on, and it starts choking and sputtering. All fluid levels are fine. I have tried cleaning the air filter (K&N), replaceing the coolant temp. sensor, let it idle for a while with the brake booster unplugged, attempting to clean out the vaccume line system, checked all vaccume lines connections, and checked the TBI wireing. I have also ran heet in my gas tank, then a higher grade gas with a fuel system cleaner added. I am at a loss, never had this happen before. It seems to run as normal if the temperature is above 50 degrees. I take that back, it did it briefly but not near as bad, acouple of years ago, I think I replaced a bigger vaccume line that went to the canister, seemed to have helped but then again it could have just gotten warmer. This vehicle has a aftermarket computer chip in it, with bigger exhaust and duel pipes No cat. on it. Please It was 12 degrees when I got off work tonight and it took me 45mins to get 13 miles to my house, because It didn't want to run over 35 mph. Almost acts like it is flooding very badly, but it is TBI. Any help / sugestions would be greatly apprieciated. Thanks in advance. Terry

[Save Old Iron 1,568]

Terry,

get the check engine codes pulled and work from there. Local Auto supply stores usually pull these codes at no cost.

TBI can still flood the engine, inlet air temp sensors can screw up at these low temps and cause very bad fuel mix info to get back to the throttle body injector. Fuel pumps could be pumping insufficient fuel at high speeds, etc.

This might be one that has to be investigated by the fault codes to give a good place to strat looking in the engine compartment

[tgranthamfd 29]

I used to know how to get the codes, myself, But I think I forgot how.

Ya know, when the light comes on, once I get off of the gas, it goes off until I put a load on it again. I haven't worked on these types of vehicles in years and I haven't had to on this one until now. It is really starting to get on my nerves or my last nerve.

[tgranthamfd 29]

Remembered the code thing, It is late but I think it flashed a 12, which isn't listed as a GM trouble code. :thumbs:

[sorekiwi 761]

Ya know, when the light comes on, once I get off of the gas, it goes off until I put a load on it again.

This probably wont help you, but years ago part of the job I had involved pulling a big 5th wheel trailer behind a Chevy dually with a 454. I was on the last trip home for the year, from Ohio to the Napa Valley in California, when the thing started to act up.

After a while I noticed that it would stumble a bit at any time you were at full throttle (which is most of the time with that big heavy trailer), but if I were to "breathe" the throttle just a little bit, it would run clean and actually accelerate. At full throttle the "Check Engine" light would come on, when I got off the gas it would go off.

I had stopped near the Bonneville Salt flats for a couple of hours sleep, and when I woke up I wondered if the fuel filter might be clogged up. I was in the middle of nowhere, so I crawled under the truck removed the fuel filter and shook it out. Red nasty crap in there. I connected it back to the tank, but the wrong way round and pumped a couple of quarts of fuel through it - a lot of red nasty crap. Put it back on the right way around and headed back down the road to California.

Man did that thing go well then, it would cruise at 75 mph without missing a beat, even up the Rocky Mountains.

Maybe its worth changing your fuel filter? :thumbs:

[bitten 134]

I was thinking fuel filter also.

[chris11 184]

Fuel pump starting to go. or dist pick up magnet broke. aslo remove vacume line off egr and test drive.

[tgranthamfd 29]

Rechecked again this morning, and it is a code 12, which is not listed under gm codes for an 88 TBI vin K. I am leaning towards fuel filter, as well. Ran all that stuff through the tank, got better then worsened. Normally at idle, no load, I can reave it up, but not this morning. Up to operating temperature and when reved it kinda sputtered some.

[nylyon-(Admin) 7,557]

Since this is an 88, OBD II scan tools aren't going to work (weren't standard until 96). If I recall, the code 12 is a normal code, you should get a code 12, followed by the real code(s) then ends with another code 12. If you have a service manual for the vehicle, it should show the codes, but again I *think* code 12 is normal.

[gwgdog66 23]

The idle air control valve is probably stuck in the extended position not letting enough air mix with the fuel. The ECM opens and closes it to keep the idle speed right. When they wear out they stick and cause all kinds of crazy stuff. When it goes out it usually will not set a code.

I have a spare I'll put on it later today.

Edit: That did need to be replaced, didn't help much. When have you last changed the fuel filter lil brother?

[tgranthamfd 29]

Drove another vehicle to work today, stopped by and picked up a new fuel filter, and put it on when I got home. Guess I have never had a filter completely plugged up before, but that fixed the problem. I feel stupid. Really apreiciate all ok the help and sugestions you guys gave. Now all I got to do is get the drip stopped. thanks.

[whfan74 2,068]

Glad it wasn't something that was more involved for you! Good luck with the drip!!!!

[gwgdog66 23]

I put teflon tape on the top half of the thread. Should work on yours also. just the top half back up close the the hex end of the fitting. That way it won't accidently get sucked into the line.