92Yoda

hey all ill start off by saying i was detailing my drivers side of the engine bay to the point of taking the whole air intake unit, coil, and other dew hickey by the master cylinder. Anyways, where I put my air filter assembly managed to fall off of what it was sitting on and hit the ground pretty hard. I finished detailing and put everything back together the way it was.

I went to start the truck and it runs like CRAP!! its idling at probly 500rpm's and sounds like a 4 cyl. also it is very smelly, and the warmer the truck gets the less it wants to run. the symptoms ive given ive looked up and have read it could and most likely is the maf sensor. the truck ran like a top right before i started this job so i know its something ive touched in the last couple days and only on the drivers side. Could the MAF sensor be damaged from the fall? thanks in advance

Slowey23

FSM will tell you how to test it too see if its faulty but are you certain that eveything went back together properly could be something not plugged in or connected properly

thook

Oh yeah! A hard fall could definitely damage the unit. You'll need to test it to verify. Search "AFM testing" and you'll turn up plenty on how to do it. It's not hard. Just need an inexpensive digital multi meter. But, like Slowey23 said, make sure everything's plugged in and correct, no vacuum leaks in the intake, etc.

Incidentally, if you're brave enough, cut the silicone away from the black, D shaped piece of plastic on the very top of the AFM unit. Pry the plastic off and visually inspect....maybe take a pic for us to see if you're not sure of what you're looking at. A soldered connection in there could have broken or something.

92Yoda

Im positive everything is plugged in back properly again, ive heard it could be a number of other things causing the problem but i havent touched them, i have however touched the maf, so im pretty sure thats whats causing the problem i just gotta test it i guess, if i had an OBD1 scanner would it be able to throw me a code saying what the problem is?

thook

You don't need a scanner. Just a paper clip.

Is the check engine light flashing at all? Turn the key to ignition and the check engine light should illuminate. If there's a stored troublecode, it will flash so many times. If there's no code, it will just illuminate solidly with no flash. That's normal, though. It just means the ECU has powered up/getting voltage....which it should be doing.

ghostgxz

Actually, when checking for codes, a constant flashing with no pauses means no codes are stored

thook

You're right, but a constant flash is not what I was referring to. I should've elaborated.

What I meant by "so many times" is, for example, it will flash maybe twice, pause for a moment, and then flash maybe four times. That's a code 24. And, again, just an example. Not saying that's the code you will get.

92Yoda

Please elaborate more on this please lol

Inferno451

There are 2 connections you jump with the paper clip to check codes and set timing. On my 87' the terminals are labeled Te and E1, and are located in the small black box next to the fuse box in the engine bay. There's a little plastic cover that hinges off and you stick the 2 ends of the paper clip in the terminals in there. Turn the key to run, count flashes to check codes.

ghostgxz

Very good info there, also, on the inside of the grey cap, the connections are labeled

http://personal.utulsa.edu/~nathan-buchanan/93fsm/

When using this link, mKe sure you scroll down to the 3vz section when you find the area you area looking for, ive made that mistake and almost ended up buying parts i didnt need

92Yoda

Thats great info ill try that out and get back to you guys

thook

Sorry 'bout that. I was posting in a hurry, really.

92Yoda

hey i went and did that test, i had an e1 and a te1 instead of just te, so i went for it anyway. i didnt run the truck just turned it to ignition, does it have to run? anyways the chk engine light flashed differently twice and my o/d light constantly flashed. the check engine light flashed once paused and flashed twice, the other pattern was flash twice pause and flash four times. im assuming that they are two different problems correct?

thook

Those were/are the correct terminals to short. And, no....don't start/run the vehicle. Just the key to ignition is all you need/should do. You're just putting the ECU into diagnostic mode.

The O/D light, if you didn't know, is the overdrive light. It will illuminate because you have an electronically controlled transmission. It works like the CEL; if there's no problem, it will flash consistently as you've seen. If there's a problem, it will flash a code in the same manner as the CEL for the EFI system.

So you did get a code 24! Ha! Kinda funny...kinda not. The other code is a 12. The code 12 is the knock sensor signal.....probably because your engine is knocking because of the AFM being damaged. Which comes to the code 24; air intake temp sensor signal. Yep, sounds like you may have damaged it....pfth! You'll need to test it. Did you run that "AFM testing" search?

92Yoda

Ahhh fantastic i had a feelin about that. Your saying the afm couldve caused the knock sensor to send that code too? Ill test the afm when i get home thanks alot for the info, hopefully this works!!!

thook

Not only will you code if the knock sensor is missing altogether (ie, a short in the wire or the sensor's gone bad), but if the engine knocks horribly enough to trigger one. A bad AFM can cause the engine to knock that bad. It affects timing/combustion to a very great degree.

92Yoda

Ok well it looks like a gotta get a neww afm to get rid of both of these problems, hopefully that fixes it because a have a 1600km trip todo tomorrow haha

92Yoda

Well went and got anpther AFM, it seems to have fixed my idling problem, but exhaust is abit smokey and smelly and whiledriving it lacks power, is it running rich? If i was to do the paper clip trick do you think another code would come up? Btw thanks a million for all the info its greatly appreciated

thook

If you haven't done it, you need to clear the old codes by pulling the EFI fuse for a few minutes before testing again.

ghostgxz

Check to see if your catalytic converter is plugged , or try removing it to see if it makes a difference, if too much unburned fuel hits the cat, or if it gets too hot, it can melt shut