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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
So my engine light is on, and not sure where to continue. I cleaned up my MAF Sensor with some cleaner, disconnected the battery and I'm still getting this code.
Unplugged it while it was on and boom, car turned off. Does that mean my sensor is done, or relays?
Turned the car on without the sensor and it started right up and slowly the rpms went down.
It's idling a little high too, and even when I turn the car off the RPM needle stays on the same spot. Any help will be appreciated.
Last edited by jorgeblancojr; 01-13-2016 at 02:40 PM.
You unplugged the sensor while the engine was running and it died. That means the ECM was using the MAF signal. While the signal may be in the high range, the MAF was still operating.
You unplugged the sensor while the engine was running and it died. That means the ECM was using the MAF signal. While the signal may be in the high range, the MAF was still operating.
What year/engine?
86 305 TPI. By the way, yesterday the car was clear of the code since i cleaned the sensor up again, so i decided to driver it around the block to test it out.
Well, it turned on on the first crank and several seconds later as i was driving the car died. I attempted to turn it on and it'll just die right away. It did it about 3 times. So i disconnected the MAF and boom it turned on and got me home.
A failing MAF due to a cracked hot wire will usually generate a 34, not a 33. Aside from circuit connections, it sounds as if the MAF itself is O.K. Circuit connections include relay contacts, reference voltage source, ECM connections, grounds, etc.
Was there a code generated when it died? What code?
If it's still a '33', there are several factors aside from the MAF which can generate the code. The code ‘33' is a higher than expected intake air flow as measured by the MAF. There are several possible contributing issues, and a little background.
The MAF measures intake air mass by the measuring the temperature difference of two sensing elements in the sensor. The MAF has two elements - one that monitors incoming air temperature, and one that monitors the temperature of the hot wire or thick film heated element. The sensor electronics package measures the current necessary to maintain the heated element temperature exactly 75̊C above the incoming air temperature. The amount of heater element current required to maintain this temperature is directly proportional to the amount of heat being removed from the element by the incoming air. Regardless of the temperature, density (altitude and barometric pressure), or moisture content of the air, the current is proportional to the actual mass of the air entering the engine. Since fuel is added by mass rather than volume, reading the mass of intake air allows the ECM to proportion fuel correctly to maintain the ideal mixture. So much for how the sensor works.
The ECM uses the MAF information to add fuel as described above. However, as a monitoring system verification of correct MAF readings, there are acceptable ranges for MAF readings under various circumstances. These allowable ranges are calculated by the ECM based on several pieces of input information. The conventions are that incoming air mass should be proportional to engine RPM, and that throttle angle will affect the amount of air available to the engine. The ECM measures RPM via the HEI module trigger input, and throttle angle via the TPS. A higher TPS voltage indicates that the engine should be moving more air at any given RPM. A higher RPM at any given throttle angle should also indicate that the engine would be moving more air. These calculations are compared to sample parameters stored in the ECM’s EPROM/CalPak. If the calculated intake is outside the allowable range for more than 600mS (6/10ths of a second) the ECM will generate and store a fault code. Once a MAF error code is stored, the ECM will ignore the MAF input for that engine run cycle and use backup fuel and spark tables entered into the CalPak EPROM. These tables are typically very conservative for spark advance and very rich on fuel.
Back to your specific situation, it seems that your ECM is measuring a higher flow than is allowed at the indicated RPM and TPS voltage. Since the range is affected by TPS voltage, and a lower TPS would demand a lower allowable intake air, it is imperative that the TPS be set properly. The acceptable range is 0.47-0.61 VDC, with 0.54VDC being the mean, or desired setting. Below the minimum is too low for the ECM to calculate an idle mixture. Set the TPS back to where it belongs. If you still experience code ‘33' DTCs, try setting the TPS to the high end of the allowable range, or around 0.60VDC. Changing the TPS upward will force the ECM to calculate a higher allowable range of intake air mass measurements, and may solve your problems.
Since you own a 1986 TPI car (like I do), I would be remiss if I didn’t mention "The Problem" with that particular year. That model was the first year with the Bosch analog MAF and new 1227165 ECM, so there was no experience other than a few factory test cars upon which to base these parameters. It seems that the engineers programmed allowable parameters and variables that were too tight for some TPI engines. While there was no recall, there is a factory TSB (# 86-6-GAS-66) regarding the problem. Several issues were addressed, including false error codes for the MAF, mixture, TCC lockup, rough idle, hesitation, etc. The problem was not addressed until October of 1986 - after the end of the model year. Thus ALL 1986 TPI engines are suspect. I installed the upgraded EPROM in my ‘86 and noticed an immediate improvement, even though I wasn’t experiencing any of the listed symptoms nor error codes.
There was also a TSB (#86-6-GAS-57) from August of 1986 regarding the code ‘33' specifically. It seems that an improper relay was used for MAF power on some engines, and the specified repair was to install a new P/N 0067925 relay in place of the original. As with any MAF error codes, the first things to check are the connectors and relays.
My advice would be:
1. Reset the TPS to 0.54VDC as a starting point;
2. Set the base timing at the factory specification of 6̊ BTDC;
3. Set the minimum air position of the throttle then re-check the TPS voltage and adjust as necessary;
4. Verify that you have the proper MAF power relay in good condition;
5. Disconnect the battery for at least a five minutes to clear all stored codes and BLM data tables. This is usually just long enough to clean the battery terminals and prevent other problems;
7. Order a replacement upgrade EPROM or burn a copy if your engine is still stock. They were about $53.00 from the dealer when released.
A failing MAF due to a cracked hot wire will usually generate a 34, not a 33. Aside from circuit connections, it sounds as if the MAF itself is O.K. Circuit connections include relay contacts, reference voltage source, ECM connections, grounds, etc.
Was there a code generated when it died? What code?
If it's still a '33', there are several factors aside from the MAF which can generate the code. The code ‘33' is a higher than expected intake air flow as measured by the MAF. There are several possible contributing issues, and a little background.
The MAF measures intake air mass by the measuring the temperature difference of two sensing elements in the sensor. The MAF has two elements - one that monitors incoming air temperature, and one that monitors the temperature of the hot wire or thick film heated element. The sensor electronics package measures the current necessary to maintain the heated element temperature exactly 75̊C above the incoming air temperature. The amount of heater element current required to maintain this temperature is directly proportional to the amount of heat being removed from the element by the incoming air. Regardless of the temperature, density (altitude and barometric pressure), or moisture content of the air, the current is proportional to the actual mass of the air entering the engine. Since fuel is added by mass rather than volume, reading the mass of intake air allows the ECM to proportion fuel correctly to maintain the ideal mixture. So much for how the sensor works.
The ECM uses the MAF information to add fuel as described above. However, as a monitoring system verification of correct MAF readings, there are acceptable ranges for MAF readings under various circumstances. These allowable ranges are calculated by the ECM based on several pieces of input information. The conventions are that incoming air mass should be proportional to engine RPM, and that throttle angle will affect the amount of air available to the engine. The ECM measures RPM via the HEI module trigger input, and throttle angle via the TPS. A higher TPS voltage indicates that the engine should be moving more air at any given RPM. A higher RPM at any given throttle angle should also indicate that the engine would be moving more air. These calculations are compared to sample parameters stored in the ECM’s EPROM/CalPak. If the calculated intake is outside the allowable range for more than 600mS (6/10ths of a second) the ECM will generate and store a fault code. Once a MAF error code is stored, the ECM will ignore the MAF input for that engine run cycle and use backup fuel and spark tables entered into the CalPak EPROM. These tables are typically very conservative for spark advance and very rich on fuel.
Back to your specific situation, it seems that your ECM is measuring a higher flow than is allowed at the indicated RPM and TPS voltage. Since the range is affected by TPS voltage, and a lower TPS would demand a lower allowable intake air, it is imperative that the TPS be set properly. The acceptable range is 0.47-0.61 VDC, with 0.54VDC being the mean, or desired setting. Below the minimum is too low for the ECM to calculate an idle mixture. Set the TPS back to where it belongs. If you still experience code ‘33' DTCs, try setting the TPS to the high end of the allowable range, or around 0.60VDC. Changing the TPS upward will force the ECM to calculate a higher allowable range of intake air mass measurements, and may solve your problems.
Since you own a 1986 TPI car (like I do), I would be remiss if I didn’t mention "The Problem" with that particular year. That model was the first year with the Bosch analog MAF and new 1227165 ECM, so there was no experience other than a few factory test cars upon which to base these parameters. It seems that the engineers programmed allowable parameters and variables that were too tight for some TPI engines. While there was no recall, there is a factory TSB (# 86-6-GAS-66) regarding the problem. Several issues were addressed, including false error codes for the MAF, mixture, TCC lockup, rough idle, hesitation, etc. The problem was not addressed until October of 1986 - after the end of the model year. Thus ALL 1986 TPI engines are suspect. I installed the upgraded EPROM in my ‘86 and noticed an immediate improvement, even though I wasn’t experiencing any of the listed symptoms nor error codes.
There was also a TSB (#86-6-GAS-57) from August of 1986 regarding the code ‘33' specifically. It seems that an improper relay was used for MAF power on some engines, and the specified repair was to install a new P/N 0067925 relay in place of the original. As with any MAF error codes, the first things to check are the connectors and relays.
My advice would be:
1. Reset the TPS to 0.54VDC as a starting point;
2. Set the base timing at the factory specification of 6̊ BTDC;
3. Set the minimum air position of the throttle then re-check the TPS voltage and adjust as necessary;
4. Verify that you have the proper MAF power relay in good condition;
5. Disconnect the battery for at least a five minutes to clear all stored codes and BLM data tables. This is usually just long enough to clean the battery terminals and prevent other problems;
7. Order a replacement upgrade EPROM or burn a copy if your engine is still stock. They were about $53.00 from the dealer when released.
Hate to say this, but I'm new to most of this and didn't understand a few things you said. To reset the TPS I'll need a Multimeter correct? As for the relay, which one is it there are a few near the firewall, and what is an EPROM? How do you install it? As for your question, the car did set a code when it turned off, but i didn't check it since i wasn't home. Now that I checked it at home it appears to be the same code 33. I apologize for my lack of intelligence in this subject.
By the way, I just turned it on with the MAF Sensor connected and it turned on, but was idling around 500. Once i gave it gas it turned off. Does that help clarify the exact problem?
Last edited by jorgeblancojr; 01-17-2016 at 10:19 AM.
A failing MAF due to a cracked hot wire will usually generate a 34, not a 33. Aside from circuit connections, it sounds as if the MAF itself is O.K. Circuit connections include relay contacts, reference voltage source, ECM connections, grounds, etc.
Was there a code generated when it died? What code?
If it's still a '33', there are several factors aside from the MAF which can generate the code. The code ‘33' is a higher than expected intake air flow as measured by the MAF. There are several possible contributing issues, and a little background.
The MAF measures intake air mass by the measuring the temperature difference of two sensing elements in the sensor. The MAF has two elements - one that monitors incoming air temperature, and one that monitors the temperature of the hot wire or thick film heated element. The sensor electronics package measures the current necessary to maintain the heated element temperature exactly 75̊C above the incoming air temperature. The amount of heater element current required to maintain this temperature is directly proportional to the amount of heat being removed from the element by the incoming air. Regardless of the temperature, density (altitude and barometric pressure), or moisture content of the air, the current is proportional to the actual mass of the air entering the engine. Since fuel is added by mass rather than volume, reading the mass of intake air allows the ECM to proportion fuel correctly to maintain the ideal mixture. So much for how the sensor works.
The ECM uses the MAF information to add fuel as described above. However, as a monitoring system verification of correct MAF readings, there are acceptable ranges for MAF readings under various circumstances. These allowable ranges are calculated by the ECM based on several pieces of input information. The conventions are that incoming air mass should be proportional to engine RPM, and that throttle angle will affect the amount of air available to the engine. The ECM measures RPM via the HEI module trigger input, and throttle angle via the TPS. A higher TPS voltage indicates that the engine should be moving more air at any given RPM. A higher RPM at any given throttle angle should also indicate that the engine would be moving more air. These calculations are compared to sample parameters stored in the ECM’s EPROM/CalPak. If the calculated intake is outside the allowable range for more than 600mS (6/10ths of a second) the ECM will generate and store a fault code. Once a MAF error code is stored, the ECM will ignore the MAF input for that engine run cycle and use backup fuel and spark tables entered into the CalPak EPROM. These tables are typically very conservative for spark advance and very rich on fuel.
Back to your specific situation, it seems that your ECM is measuring a higher flow than is allowed at the indicated RPM and TPS voltage. Since the range is affected by TPS voltage, and a lower TPS would demand a lower allowable intake air, it is imperative that the TPS be set properly. The acceptable range is 0.47-0.61 VDC, with 0.54VDC being the mean, or desired setting. Below the minimum is too low for the ECM to calculate an idle mixture. Set the TPS back to where it belongs. If you still experience code ‘33' DTCs, try setting the TPS to the high end of the allowable range, or around 0.60VDC. Changing the TPS upward will force the ECM to calculate a higher allowable range of intake air mass measurements, and may solve your problems.
Since you own a 1986 TPI car (like I do), I would be remiss if I didn’t mention "The Problem" with that particular year. That model was the first year with the Bosch analog MAF and new 1227165 ECM, so there was no experience other than a few factory test cars upon which to base these parameters. It seems that the engineers programmed allowable parameters and variables that were too tight for some TPI engines. While there was no recall, there is a factory TSB (# 86-6-GAS-66) regarding the problem. Several issues were addressed, including false error codes for the MAF, mixture, TCC lockup, rough idle, hesitation, etc. The problem was not addressed until October of 1986 - after the end of the model year. Thus ALL 1986 TPI engines are suspect. I installed the upgraded EPROM in my ‘86 and noticed an immediate improvement, even though I wasn’t experiencing any of the listed symptoms nor error codes.
There was also a TSB (#86-6-GAS-57) from August of 1986 regarding the code ‘33' specifically. It seems that an improper relay was used for MAF power on some engines, and the specified repair was to install a new P/N 0067925 relay in place of the original. As with any MAF error codes, the first things to check are the connectors and relays.
My advice would be:
1. Reset the TPS to 0.54VDC as a starting point;
2. Set the base timing at the factory specification of 6̊ BTDC;
3. Set the minimum air position of the throttle then re-check the TPS voltage and adjust as necessary;
4. Verify that you have the proper MAF power relay in good condition;
5. Disconnect the battery for at least a five minutes to clear all stored codes and BLM data tables. This is usually just long enough to clean the battery terminals and prevent other problems;
7. Order a replacement upgrade EPROM or burn a copy if your engine is still stock. They were about $53.00 from the dealer when released.
Ok i adjusted the tps to .54v it was on .58v. I then disconnected the ecm and negative battery for 5 minutes. I turned it on with the maf sensor connected and it just turned off a second after i turned it on. It did this about 4 times. So i disconnected the maf sensor and it stayed on. Also i checked the codes and didn't get anything with the maf connected and all.
Last edited by jorgeblancojr; 01-17-2016 at 06:49 PM.
01-13-2016, 02:35 PM
