C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Solving MAF Code 33 Problem

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Old Jul 14, 2008 | 01:46 AM
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Default Solving MAF Code 33 Problem

A few days ago, I noticed that the car was not running smoothly at throttle-off while cruising on the highway. Then it set a code 33 and wouldn't idle well at startup; then needed some throttle start, especially cold (well, for this time of year, anyway). Being short on time, I replaced both MAF relays with a couple I happened to have on hand. It started up and idled fine--no code. I drove it for 2 hours (about 100 miles) and it ran smooth--thought I had solved the problem. Later, it was hard to start again and idled rough and it set the code 33 again.

Any thoughts on why replacing the relays would temporarily help? Can a bad MAF damage the relays? (I wouldn't think so, but... anything is possible, I suppose).

I'll unplug the MAF and drive it tomorrow, but was just wondering while I'm in the middle of figuring this out.

I've been offline for a while (seriously consumed with house projects and life stuff), so you guys were a great help when I searched for info on Code 33 and found all your tips and experience. The forum is awesome!
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Old Jul 14, 2008 | 09:04 AM
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http://members.shaw.ca/corvette86/Code%2033.pdf
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Old Jul 14, 2008 | 10:15 AM
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When you really get down to reading the FSM you'll find the fuel pump relay also plays a factor in the MAF function. Not quoting it again. But check the wire insulation on the back side of fuel pump relay. On my 87 they were shrunk back from heat and some were coming into contact with others.
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Old Jul 14, 2008 | 11:19 AM
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Originally Posted by rick lambert
When you really get down to reading the FSM you'll find the fuel pump relay also plays a factor in the MAF function. Not quoting it again. But check the wire insulation on the back side of fuel pump relay. On my 87 they were shrunk back from heat and some were coming into contact with others.
Thanks, I'll be sure to check that. I do have the FSM, but need to find all my tools and meters and such if I'm going to be able to run the full diagnostic... and the time. It seemed quicker to replace the relays... as others have said, "relays first".

We'll see how it runs today with the MAF unplugged. I looked back at my records and discovered I replaced the MAF less than 2 years and 8,000 miles ago (it seemed longer than that), so it will suck if that's all the longer the MAF lasted.
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