Needs some help please. today i took apart my air box to clean and what not. i found that my airbox is very restricktive. So i grinded away all the extra placstic that was restricking my air flow. clean it up very nice looks stock. Anyway with the MAF sensor off i took a look at it and notice it was a little black so i took some gum cutter and clean it and blow it out with compressed air knowing not to damge it the hair like wires. Put it all togther and fired it up and test drove it.

Found that my idle is jumping up and down almost cutting the car off and my MPH went from 22-23MPG to 14-15 MPG.

After this i bypassed the MAF sensor and fired it up again. still same results with the up and down idle.

I think i f##@ it up by spraying gum cutter in it? Or does my eprom need to be reprogrammed.

If the MAF is broken is there anyway to fix it or test it. Or is my air box somehow messing things up?

i have a OBD1 useing datamaster will that help me better understand whats up?

Also no check engine light even when i unplugged the MAF maybe i didn't wait long enough?

I also disconnected the battery for the hell of it and tried again.

 

Try giving the MAF a gentle tap with the back of a spoon, if the idle significantly changes, then usually the MAF is no good.

 

Nope no luck still runs the same.
If i hook up the data master scan tool will that tell me anything?

I found a Microtech MAF from Advance auto. Is that a bad idea? I also went to MId America and found a adjustable one from $369
but i'd still like to make sure my MAF is bad.

 

Connect a voltmeter to the MAF output, start the engine, and read the MAF output voltage.

 

Sorry i'm gonna sound stuiped but there are i think 5 pins. Which ones should be the out put and what should the voltage read?

 

Dark Green is the output wire, but I am not 100% sure what it should read with a volt meter. I always checked mine through WinALDL or Datamaster.

 

dude what do i look for in WinALDL or Datamaster? how do i check it i don't have check engine light?

 

You need a ALDL cable to use WinALDL, or Datamaster. They are fairly cheap off ebay, 20 - 40 bucks or so.

After that, you choose which ECM you are running (Unless its an 85, you'll have a 1227165 ECM.

Once you are all setup, start the car up, and look at the reading for the MAF. Mine was something like 20 g/s or so -- But, my MAF never worked correctly, and I am switching to speed density, so I am not sure if that is a correct value.

Someone else will be able to help you out there

 

is speed denisty better cheaper?
Anyone no what grams it should be reading?
thanks for the tips man i'll check her out soon.

 

Speed density is technically a simpler system. Simplifies air ducting, just replace the MAF with a cone filter and eliminate the restrictive air box (at least with the Trans Am air ducting I am using), eliminates the MAF power and burnoff relays, along with the external EST system.

Speed density also has the potential to perform a bit better than a MAF, simply by removing the MAF, its a bit of a bottle-neck, and removing it allows more air into the engine.

I figure I'll have something like 100 bucks cnd into the swap when all is said and done (50 bucks for the SD ECM, 15 bucks for a MAP sensor, couple cents for a resistor to make my old MAF knock sensor work, another 15 - 20 bucks for a paper cone filter, and the rest on anything else unexpected I run into along the way.

I will also be doing my own prom for the speed density setup, so that was also a huge deciding factor. A MAF is a fair bit more leniant with engine changes than a speed density setup is.

 

So it sounds pretty easy. When you say new ECM do you mean the entire ECM or just the Eprom(reprogram a bin into the Eprom)?

The other day i looked around to see if i could find MAF to SD swap but found nothing much. Do you have link describing the swap?

Oh anther thing i plan on putting a super charger on this thing later down the road with a 383 stroker. I'm guessing that the MAF setup must go right? That bottle neck with be a hugh bottle neck. I ported my upper and lower intakes and runners and didn't even notice the freaking air box till a couple days ago hahaha. i should really feel a change once i buy the MAF senor. So that sucks I never notice how restrickive the air box and the MAF till i took it all a part the other day and fixed it. What a joke! Guess GM really did try to cut down fuel in the 80's. i might fork out the money for a microtech MAF they are life time warrenty 168 buckx

 

Yeah, you need to change the entire ECM, they are very different.

If the MAF is all that is wrong with your setup, I'd personally recommend that you just buy the new MAF, read up on the speed density conversion, and do your swap when you know exactly what you'll need to do

Esspecially if you have done a bunch of porting and stuff, and don't know how to burn your own chips. They are typically 50 bucks a pop from most places, and thats just to get you in the basic ballpark, for your engine to truely run to its fullest potential, you need to either run your car on a dyno, time after time, and program the chip that way, or drive, look at your datalog, and make a chip that way instead.

In my case, I'm still building my truck, and switching to speed density will solve a fair number of issues I was going to have to deal with when running a MAF.

Here is a link to a site full of information on the speed density swap:

http://www.eecis.udel.edu/~davis/z28/ecm_swap_730/

 

Thanks alot man I'm going to hopefully monitor my MAF today with my datalogger see what it's doing. You no know that i think about it I think my MAF has slowly been dying because the car has been running way to lean lately and started up takes a while. Plugs look like they are brand new from the lean mixture. The whole time i've been thinking my porting caused this lean mixture. ANd now all of a sudden MAF just totally crapped out. I'll post my MAF readings once done. i want to make sure it's really a MAF not a relay or what not. Damn i wonder what kind of preformance i'll get after replacing this stuiped thing. The sad part is the stuiped check engine light never came on. I'll see what i see via data log.

 

Post that log up here too, so we can take a look. Might be a problem with a different sensor, such as the 02 sensor or something as well

 

cool man really apresheate it. i'll get on it soon. You've been a great help.

 

It could be that when you cleaned out the MAF that you got something on the wire that would cause it to read incorrectly.

As we all know the MAF is given a current, and it heats up, as the air passes across the wire it cools off and changes the resistance. The computer compares the reading to the air temp in the plenum. IF by chance that gum cutter got on the wire it could have changed the properties of the wire.

If it was me I might try taking brake cleaner (I ASSUME NO RESPONIBILITY IF YOU TRY IT) and try to clean off the wire. preferably something that leaves no residue. You have nothing to lose at this point.

DISCLAIMER:
--- I take no responsibility if you choose to try any suggestion that I post as I do not have the entire amount of information available to me to do a through investigation to why whatever is not working correctly, do anything I suggest at your own risk! ---

John

 

yeah did that too, the brake didn't help much i also tryed the rubbing alchol with the same results. I'm kinda stuiped for using gum cutter, oh well you live you learn. i'm gonna log it just for the hell of it then post my results here in a few.

 

Ok i did a datalog. I have 2 uni dumps. It looks lean as hell to me. but no codes. BTW the O2 sensor was replace like a month ago.

I need to get more involded with the the data logging, but it pisses me off. reason being is that it takes for ever for it to work, sometimes it syncs sometimes it doesn't its not the greatest tool. I use Datamaster not sure if it's the program? I don't think its the cable, it's a moates OBD1- usb cable. I just can't get it to sync up sometimes anyone have this same problem? if so tips would be greaty appreshated.

Also how should i upload these uni files?

thanks again

 

I have to turn on the car without starting it and then start my computer. Then sync with the car. I am using the APU1 the whole shebang...

Try the tunerpro software, its pretty easy to use... I like it, I had the same problems, until I realized there was a sequense I had to go through... I also purchased a copy of tunercat as it has some funcitons that the tunerpro software did not. It alows me to turn off the EGR malfunction code etc.

Turn on car - starting is not necessary
turn on computer connected to car
run program
connect to ECM and OBD connection
upload the program to ECM

away I go...

Sometimes it just decides to kick me out and my dataloging session is over until I can pull over and reboot everything but I can go usually about 10 to 20 min between sessions, it gives me enough to screw with.

John

John

 

OKFOZ, I'll give it a shot with the different software, but as far as order goes i have that down right.

80Sierra, can you take a look at my UNI files. Can you give me a email addy let me know what you think?

Thank You

 

Not sure how to check UNI files, but send em to Russell (at) ZieglerDigital.ca and I'll figure out what to do with them and see what I can find

 

It's a datamaster log file. So datamaster will open them right up. i'll try using Tunerpro too tommorw come morning.
Hey man thanks alot for your help. So it's Russell@ZieglerDigital.ca i'll email them today. I'll zip them first just in case virus protect blocks them.

thank you

 

You have email

 

Oh, I forgot to mention I am using Tunerpro R/T

John

 

Cool thanks John. i'll need to try Tuner Pro R/T. I've tried with Winaldl again it seems to log but not much it only gave me like a couple numbers haha. Humm I'll try WinALDL again too. Well i took it for a run this last time after cleaning my IAC and recalibration know it was running like crap. My car still runs the same to say the least. It stalls out at Idle and seems like it's not running at it's fullest.

2 question please.

1.) Will a bad IAC trip up a trouble code?
2.) Will a IAC make my car feel like it's misfiring then clear up.


My guess is in might be my IAC maybe because a MAF will trip trouble code right?

Once i get a little extra cash i might just get both MAF and IAC from Advance Auto. I'll try IAC first though.

Thanks To everyone

 

can anyone please help me answer these queestions.
They might sound stuiped but anything will help please.


1.) Will a bad IAC trip up a trouble code? because i have no trouble codes
2.) Will a IAC make my car feel like it's misfiring then clear up.

thanks

 

The IAC (Idle Air Control) moves in and out via motor, that if its too lean will turn in the pintle, and if its too rich will move out the pintle. It could make it run rough, if it does not allow enough air in.

If it seems to clear up once its warm you may consider checking the temp sensor for the ECM thats on the front of the intake manifold. My car when I got mine together for the first time it would not hold idle, but once it got warm it was perfect.

A rough idle could be caused by the bad MAF unless you have already changed that out

Also check to see if your throttle body is set up correctly.
- Warm your car to operating temp.
- Jump A & B
- Turn on car, and get the blinking 1...2...1...2
- Then you unplug your IAC
- disconnect the jumper
- Start the car with the IAC unplugged, and set your minimun idle, I think its 500 for auto and 550 for manual, but you will have to check that too, depending on your engine etc. To do this you turn the little set screw on the drivers side for the TB stop.
- once your at the correct idle, reset your TPS to .54V

Its been a while, verify this in a Haynes or Chiltons manual.

John

 

Thanks man 80Sierra help me reset my IAC clean and recalibrate. Runs pretty much like crap too warmed up, not as bad, but not good.. I wish it would give me a silly trouble code. I think my only help is to get a OBD 1 scanner on it or try Tuner Pro R/T and log it badly. Otherwise i'll be spending money on sensors. well i'll keep everyone posted on it.

Thank You

 

A fairly stock L98 should produce enough air flow at a 800-900RPM idle to have the MAF report about 900mV.

ECM programming is pretty stringent in the MAF tables. If the MAF does not report an acceptable level of air flow at any given RPM and throttle angle, the ECM should set a code within 600mS. The tables are not very forgiving.

 

Right meaning in my case that the MAF might not be my problem if it has not thrown a code yet right?

I'm gonna try to run the steps again for a IAC Calbration. then log her again see what i get.

Pretty much runs like crap i'm very surprized it has not thrown some kinda code. oh well i bought this riding knowing what issues i'd run into so just gotta fight'um out.

 

"Runs like Crap" what do you mean? Is the idle unstable? Does it run rough with lots of black smoke?, Does the idle go up and down irratically slowly getting better?

Your description is virtually uslesess unless you give us exactly what is going on.

I still think since it runs fine when warm that the temp sensor is out of whack since its temp related... $12 at most parts stores. What does it read when you fire it up for engine temp on your computer? The gage uses a different sensor.

John

 

Yep the idle unstable. runs rough with lots of black smoke. the idle goes up and down irratically. Does not really get much better after getting warmed up. Once it's warm it goes through like cycle of runs good then dies (unstable, runs rough, idle up and down) over and over again it does it prefect like every 10 seconds for example. even in drive. it's driveable to a point but not very safe.

I'm getting ready to run through a bunch of steps again with my data logger today. i'll keep you'll posted.

Thank You

 

IAC appears to be working properly, as the up and down idle would indicate. A bad IAC typically will not idle, or it will not compensate.

When you datalog, pay attention to details that would be temperature specific.

John

 

Ok I finally gotta pretty good log going. BTW if anyone runs into trouble with there scan tools no connecting try dropping the baud rate transmit and receive bits to 2432. It works!

Ok so i've notice my IAC postion stays right at 160 (is that normal?)the entire time and my IAC min bouces around alot. I didnt drive it but just let it hit closed loop. Once it hit closed loop it really smoothed out. My IA temp is off by 2-5 deg at best, think thats normal. temp sensor seems ok

Also my TPS is at .73 at idle. I'll need to adjust thats for sure.



Sorry this short but i'll give a better descption tommorw. time to sleep soon.

still not luck with winaldl but will try again soon. again sorry for the shortness.

 

Get the TPS voltage adjusted first. That should eliminate some possibilities. After it's adjusted and you start up, pull the vacuum hose from the FPR and see if there is any liquid fuel present.

 

Ok fixed for the most part woooo hoooooo. Damn what a pain in my a$$. The IAC motor was working in the forward postion but not able to retrack the pintal. I replaced the IAC works great, recalabrated too. Then i adjusted my TPS to .54 volts. All this head ache because for the most part my scanner kept crapping on me and it was not able to give me information till the other night.

Well test drove it, it came back to life i smoked my tires and pushed my car up the street sideways for a while. hehe

One thing came up after this, the code 36 burnoff. I parked her back in the garage disconnected the battery and test drove again and ran fine. I'm gonna drive it tonight and see if it trips the code again.

Feels good to be able to drive it like normal again. Man all this because i found a restrickion in my air box. BTW unrestricking my air box really brang out my porting job i did in the past. My top end has ***** now!

thanks everyone.

 

Glad to hear you got her up and running

With everyone else getting back on the road, I think its time to get mine fixed already :P Maybe have some time this week

 

Thanks For your help man, good luck with your ride too.