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Hello from Sweden, My 88 Callaway twin turbo is completely restored but for one little problem, a code 34. My original MAF got water inside the housing and never worked after that. (code 33 even with it plugged in) I purchased a reman MAF and installed it with an almost immediate code 34. I then went out and bought new power and burn off relays, no change. I should mention that I have a new O2 sensor and IAC. I adjusted the IAC and the TPS to the shop manual Idle specifications. I then bought a used MAF in working condition from an 87 trans am which threw the same code 34. I have tested the signal at the MAF connector from the ECM at 5v ignition on MAF unplugged and 2.4v plugged in ignition on engine stopped. When I start the engine I get .17v to near .3v on the (green) signal wire at idle with my digital meter. I get 12v on the purple wire, ignition on engine off and near 14v engine on. Grounds have been checked at the MAF connector and are good. I am nearing my wits end and I'm considering getting an MAF from Blower works. It is much better than original OEM but requires some modification to the ECM harness and new Eprom not to mention $300-500 depending on accessories. I guess I am just looking for any possible problems I may have overlooked before I spend the cash on a new MAF so any advice would be greatly appreciated.
I'd hook a scanner to it and see what the reported flow rate is at various RPMs. You could have a bad ground somewhere else or other issue that's causing the code. What's important is what the ECM sees,
I'd hook a scanner to it and see what the reported flow rate is at various RPMs. You could have a bad ground somewhere else or other issue that's causing the code. What's important is what the ECM sees,
If only testing a MAF was this easy. You can't export data fast enough and bench testing is all but impossible without specialized equipment.
I was also in the same boat with a MAF on my L98 IROC, but mine was a code 36. Burnoff. Mine had a new style thin hot film design. So, I ordered a re-manufactured Bosch OEM unit with the original hot wire design. Caused all kinds of running issues in open loop.
The Blower works MAF is a good but expensive option. Actually, MAFs are just expensive these days.
A Code 34 could be a few things though. I too would suggest doing some scanning and data logging, but look at more than just what the MAF is saying. You still need to look at the BLMs, INTs, IAC, TPS, MTS and CTS to make sure the rest of the system is truly healthy. Have you reset the ECM since the change? Also, FSM says to replace your relays with a MAF change. Your 34 says it is getting less air than it thinks it should be. What are you TPS volts at Idle? Does it have a smooth sweep? How is your IAC health?
If only testing a MAF was this easy. You can't export data fast enough and bench testing is all but impossible without specialized equipment.
I was also in the same boat with a MAF on my L98 IROC, but mine was a code 36. Burnoff. Mine had a new style thin hot film design. So, I ordered a re-manufactured Bosch OEM unit with the original hot wire design. Caused all kinds of running issues in open loop.
The Blower works MAF is a good but expensive option. Actually, MAFs are just expensive these days.
A Code 34 could be a few things though. I too would suggest doing some scanning and data logging, but look at more than just what the MAF is saying. You still need to look at the BLMs, INTs, IAC, TPS, MTS and CTS to make sure the rest of the system is truly healthy. Have you reset the ECM since the change? Also, FSM says to replace your relays with a MAF change. Your 34 says it is getting less air than it thinks it should be. What are you TPS volts at Idle? Does it have a smooth sweep? How is your IAC health?
TPS is .54v and IAC is new and adjusted correctly with timing a 6 degs. Relays are also new. What do you mean by resetting the ECM? Do you mean removing any codes by disconnecting the ground from the battery, if so, that is done religiously. The car runs OK other than the surging idle in the warm up but once I hit around 180 the idle settles down and you would think nothing is wrong if you don't give it gas. I don't know what you mean by smooth sweep? What are BLM's, INT's, MTS and CTS?
I have ordered an ALDL cable and with any luck I will be testing this weekend. I really want to have this all sorted out before shelling out the big bucks for a BW MAF and Tuning from Moates.
TPS is .54v and IAC is new and adjusted correctly with timing a 6 degs. Relays are also new. What do you mean by resetting the ECM? Do you mean removing any codes by disconnecting the ground from the battery, if so, that is done religiously.
Yes, this does more than just reset codes. There are long term fuel trims learned that you are also clearing, but this is what I was asking.
Originally Posted by Cski1968
The car runs OK other than the surging idle in the warm up but once I hit around 180 the idle settles down and you would think nothing is wrong if you don't give it gas.
I have ordered an ALDL cable and with any luck I will be testing this weekend. I really want to have this all sorted out before shelling out the big bucks for a BW MAF and Tuning from Moates.
I felt the same way, but the BW MAF may be the ticket when I go to do anymore engine mods.
0.17-0.3 volts represents very low air flow for a running engine (approx. 3-4 gm/sec). For reference, ~8 gm/sec is typical flow at idle for a 5.7 liter L98.
The code 34 failure is set below 7 A/D counts (or ~0.14 volts) which appears to be in the ballpark from your posted measurements. These readings do not suggest a short to ground.
First check for air leaks all the way between the MAF sensor and the intake manifold.
With a Callaway, you have a lot of extra plumbing (tubing, couplers, turbos, intercoolers, rams horn) that could be leaking and allowing intake air to bypass the MAF sensor. Vacuum leaks are another possibility that could contribute to low MAF flow readings, but I would bet on a significant air leak upstream of the throttle body due to the size and number of components that could be a source of an air leak.
Data is always helpful, so proceed with your plan to log data with an ALDL cable and appropriate software.
Update: I spent the last week going through connections, vacuum hoses and grounds with a stainless steel brush and some conection cleaner. Today I got everything back together and started her up, Code 34. C**T. I was beatin so I decided to clean up the garage and wait for the ALDL cable toget a better under standing.
I was just looking over the second MAF that was used but not rebuilt, while cleaning, and just noticed the sensor filiment had a break which I didn't see before. So now what, since I have some time, I decided to summon my inner Frankinstein and see If I could merge my original MAF which had a water soaked board but a good sensor filiment. Ureaka! it F'n worked. no more code 34 good idle. I really did think it could be done. see pics
It's not pretty soldering but did the trick
Update: I spent the last week going through connections, vacuum hoses and grounds with a stainless steel brush and some conection cleaner. Today I got everything back together and started her up, Code 34. C**T. I was beatin so I decided to clean up the garage and wait for the ALDL cable toget a better under standing.
I was just looking over the second MAF that was used but not rebuilt, while cleaning, and just noticed the sensor filiment had a break which I didn't see before. So now what, since I have some time, I decided to summon my inner Frankinstein and see If I could merge my original MAF which had a water soaked board but a good sensor filiment. Ureaka! it F'n worked. no more code 34 good idle. I really did think it could be done. see pics
It's not pretty soldering but did the trick
Good deal, the Iroc in the Vid I posted was solved with a MAF swap as well.
0.17-0.3 volts represents very low air flow for a running engine (approx. 3-4 gm/sec). For reference, ~8 gm/sec is typical flow at idle for a 5.7 liter L98.
The code 34 failure is set below 7 A/D counts (or ~0.14 volts) which appears to be in the ballpark from your posted measurements. These readings do not suggest a short to ground.
First check for air leaks all the way between the MAF sensor and the intake manifold.
With a Callaway, you have a lot of extra plumbing (tubing, couplers, turbos, intercoolers, rams horn) that could be leaking and allowing intake air to bypass the MAF sensor. Vacuum leaks are another possibility that could contribute to low MAF flow readings, but I would bet on a significant air leak upstream of the throttle body due to the size and number of components that could be a source of an air leak.
Data is always helpful, so proceed with your plan to log data with an ALDL cable and appropriate software.
OK, Finally got my ALDL and setup TunerPro RT for some data logging. this is what I have so far.
BLM 143 unless I goose the throttle then it goes down to 129 (this was a red flag for me)
INT 128 constant throughout warm-up
Target AFR 14.22- 14.73
Injector base pulse width 2.0 +/- .2
IAC started around 60 settled to around 18 when warmed up
at Idle MAF started around 9.00 G/sec at 800-850 rpm's when warm 7.50 at around 750 rpm's
O2 ranged between 450mV to 700mV when warm in closed loop
Just a side note, I have noticed that my Fuel pressure has dropped starting a couple weeks ago. During the rebuild I replaced the fuel filter with the new injectors and added a pressure gauge. In the beginning the gauge read between 40-45 at idle but lately it's been around 32-36 and can reach 40 if I goose the throttle. seems low because Callaway added a high volume pump in the CTTC cars. Car was sitting for 12 years maybe the filter picked up something?
0.17-0.3 volts represents very low air flow for a running engine (approx. 3-4 gm/sec). For reference, ~8 gm/sec is typical flow at idle for a 5.7 liter L98.
The code 34 failure is set below 7 A/D counts (or ~0.14 volts) which appears to be in the ballpark from your posted measurements. These readings do not suggest a short to ground.
First check for air leaks all the way between the MAF sensor and the intake manifold.
With a Callaway, you have a lot of extra plumbing (tubing, couplers, turbos, intercoolers, rams horn) that could be leaking and allowing intake air to bypass the MAF sensor. Vacuum leaks are another possibility that could contribute to low MAF flow readings, but I would bet on a significant air leak upstream of the throttle body due to the size and number of components that could be a source of an air leak.
Data is always helpful, so proceed with your plan to log data with an ALDL cable and appropriate software.
Ok, Here is the results of my first Data log from TunerPro RT
INT 129 steady from cold to warm
BLM 143 all the time except when I goose the throttle, then goes to 129
INJ base pulse width 2.0 +/- .2
IAC 55 cold 18 warm and closed loop
MAF 9.00 g/sec cold at 950 rpm's 7.5 warm 750 rpm's 6.50 closed loop
AFR 14.2-14.73
O2 450mV to 750mV closed loop
MAT 132.5 warm closed loop
Always rich when idling. Just a side note, I have noticed that my Fuel pressure has dropped starting a couple weeks ago. During the rebuild I replaced the fuel filter with the new injectors and added a pressure gauge. In the beginning the gauge read between 40-45 at idle but lately it's been around 32-36 and can reach 40 if I goose the throttle. seems low because Callaway added a high volume pump in the CTTC cars. Car was sitting for 12 years maybe the filter picked up something?
Re-manufactured Maf Bad? Code 34
