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Attached are the readings from my 1988 all stock Anniversary. After not driving it very much since earlier in the year I've started driving it again and have put several partial tanks of fresh gas in it. Several weeks ago I had this similar situation with a 33 MAF High. After research I disconnected. reviewed and reattached the MAF sensor connector. All was good. Went to fill it up with premium yesterday late since I'm driving to the Pier Show tomorrow and the Service Engine Soon indicator came on. The other "funny" thing is that the engine will be idling at 6-7K, and then once in awhile drop to 4K and then just quit. This is a new situation that I've never had either. Seems like they are connected.
Thoughts on fixing? OK to drive it as is at 70 MPH for 75 miles each way?
Hopefully the attachments aren't doubled up since we're having ISP speed issues.
I have an '87 that started throwing. Code 33 a few years ago.
Initially it seemed to be temperature related as the condition would occur when the engine was hotter. The first time it happened was shortly after I replaced my radiator,mwhich had plastic sides, with an all metal radiator. If I was in traffic, and the oil and/or coolant temp got a little high (around 220 degrees) it would throw a code. When the cooler weather of winter cem along (I live in Los Angeles county), the problem disappeared for a while, but resurfaced when the weather warmed up again. Eventually it was throwing a code all the time. I replaced both burn off relays (always begin by replacing the cheapest parts), and I replaced the MAF sensor 5 times. The first two were Delcos, the next was a Bosch, and the next was an A Cardone, before going back to a Delco. All of these were new, not rebuilt, and all were in the $50-$75 price range. I also replaces the ECM three times, which led me down a-whole-nuther series of problems. Eventually I returned to the original ECM only without the performance chip. It didn't matter what MAF sensor I used, the problem persisted. When it throws the code, the car goes into LIMP HOME MODE.Finally, I went straight to Chevy thinking that I would just dump this problem in their lap--hey, they're the experts, right? Well Chevy will not troubleshoot past the code. Since the code says it is the MAF sensor, they won't do anything else until you let them replace the MAF sensor, regardless of the fact that it has already been replaced 5 times with no improvement. They claim that their MAF sensor, which costs $1,500, is more accurate. Oh, and, by the way, it is not guaranteed to fix the problem. It's not like the MAF sensor is an intricate electronic circuit either. The MAF sensor is simply two heated wires in the intake path. The wires heat up and the air coming in cools the wires as it passes through the tube. This tells the ECM how much gas the fuel injectors should provide. Anyway, I am now back to the OEM Delco MAF sensor. I also replaced the radiator with a bigger one with plastic sides, and I replaced the exhaust with true dual 3.5" exhaust pipes, cats, and mufflers. Currently, my car still throws a code. However, I noticed that if I disconnected the battery, when I started the car, there was no code. But if I shut off the car, the code appears as soon as I start it again, no matter if the engine is warm or totally cold, and it no longer matters what the temperature is outside. Frustrated and out of ideas (other than replacing the wiring between the MAF and the ECM, UGH!), as a workaround to manage the problem, I installed a heavy duty SPST lever on the negative terminal of my battery. If I disco and reconnect that throw switch, my car (most of the time) will run for hours without throwing a code. If I am in traffic, it will be hit or miss, sometimes yes, sometimes no, but if I am on the highway cruising at 70mph between 1800 and 2200 rpm, the car will run like a top until I turn off the ignition. If I start it again without clearing the ECM with that switch, it immediately throws a code.This has been the most frustrating problem I have ever encountered in over 45 years of working on cars. So, I mean this when I say, good luck.
Yesterday was interesting. Was driving to the caravan location at about 45 MPH and after about 15 minutes when there was several "hiccups" where the engine coughed and the SES light came on immediately. At the meeting point shut the car off and restarted it about 15 minutes later when it's really heat soaked. For the 60 miles up the Pier monitored the instant fuel economy and all was fine. After the show it got a good warmup because it took a long time to get out onto the freeway. Drive the entire 75 miles without incident even with several Florida downpours.
I was going to just pop for a MAF probably from our favorite local C4 used parts dealer in Sarasota but after reading this that might be a waste of time and money. I've looked at other posts again one of which reminded me that years ago in Minnesota I ended up just replacing two relays to get rid of an SES error. The dealer could only offer to replace each component in the entire car until the problem went away. There informal estimate was 2-3K for parts and labor.
What are the thoughts that If I run my laptop continuously monitoring the OBD1 why I drive that I might get a better handle on what's causing this problem? Could it be a gasoline quality problem?
I have an '87 that started throwing. Code 33 a few years ago.
Initially it seemed to be temperature related as the condition would occur when the engine was hotter. The first time it happened was shortly after I replaced my radiator,mwhich had plastic sides, with an all metal radiator. If I was in traffic, and the oil and/or coolant temp got a little high (around 220 degrees) it would throw a code. When the cooler weather of winter cem along (I live in Los Angeles county), the problem disappeared for a while, but resurfaced when the weather warmed up again. Eventually it was throwing a code all the time. I replaced both burn off relays (always begin by replacing the cheapest parts), and I replaced the MAF sensor 5 times. The first two were Delcos, the next was a Bosch, and the next was an A Cardone, before going back to a Delco. All of these were new, not rebuilt, and all were in the $50-$75 price range. I also replaces the ECM three times, which led me down a-whole-nuther series of problems. Eventually I returned to the original ECM only without the performance chip. It didn't matter what MAF sensor I used, the problem persisted. When it throws the code, the car goes into LIMP HOME MODE.Finally, I went straight to Chevy thinking that I would just dump this problem in their lap--hey, they're the experts, right? Well Chevy will not troubleshoot past the code. Since the code says it is the MAF sensor, they won't do anything else until you let them replace the MAF sensor, regardless of the fact that it has already been replaced 5 times with no improvement. They claim that their MAF sensor, which costs $1,500, is more accurate. Oh, and, by the way, it is not guaranteed to fix the problem. It's not like the MAF sensor is an intricate electronic circuit either. The MAF sensor is simply two heated wires in the intake path. The wires heat up and the air coming in cools the wires as it passes through the tube. This tells the ECM how much gas the fuel injectors should provide. Anyway, I am now back to the OEM Delco MAF sensor. I also replaced the radiator with a bigger one with plastic sides, and I replaced the exhaust with true dual 3.5" exhaust pipes, cats, and mufflers. Currently, my car still throws a code. However, I noticed that if I disconnected the battery, when I started the car, there was no code. But if I shut off the car, the code appears as soon as I start it again, no matter if the engine is warm or totally cold, and it no longer matters what the temperature is outside. Frustrated and out of ideas (other than replacing the wiring between the MAF and the ECM, UGH!), as a workaround to manage the problem, I installed a heavy duty SPST lever on the negative terminal of my battery. If I disco and reconnect that throw switch, my car (most of the time) will run for hours without throwing a code. If I am in traffic, it will be hit or miss, sometimes yes, sometimes no, but if I am on the highway cruising at 70mph between 1800 and 2200 rpm, the car will run like a top until I turn off the ignition. If I start it again without clearing the ECM with that switch, it immediately throws a code.This has been the most frustrating problem I have ever encountered in over 45 years of working on cars. So, I mean this when I say, good luck.
Update:
Still throwing code 33. Replaced MAF sensor (3 times), Burn-off relays, ECM (Twice), Fuel Pressure Regulator, Valve guide seals, Alternator (3 times), Radiator (Twice), Complete exhaust to the heads, as well as a million unrelated parts (Power Steering, fan, Master cyl, PS Boster, AC Compressor, fan, horns, etc), I finally installed a kill switch on the battery so I don't have to unscrew terminals every time to disconnect the battery and clear the code but I still have to open the hood every time. My gas pedal started binding, so they replaced my throttle body, but now it wont take the gas--put the old throttle body back on and the problem persisted. Mechanic is baffled. Been running 2 or 3 bottles of Techron for each tank of gas, and it has been running better with each tank, but then out of the blue, it wont take the gas again intermittently. Meanwhile, I am still throwing Code 33. I suspect that when I had that valve guide problem and my car was blowing soot at start up, that it mucked up my exhaust components like the EGR (Exhaust Gas Return) valve, and related components and perhaps the exhaust port in the plenum. These parts should have been replaced when the mechanic took off the plenum to get to the Fuel Pressure Regulator, but he didnt. That job cost me $600, so I am hesitant to remove the plenum again to replace those components. What else can cause me to throw Code 33?
One of the guys in my Corvette club had to get a NOS MAF off of EBay for his 87 Corvette. He said the replacement ones from the auto stores didn’t have the correct wire in the MAF for the computer to do the burn off sequence. He kept getting the code 33 until he found the NOS one on EBay. Kevin
33 MAF High Error
