weird engine problem please help

jmfasc

Registered User
ok, let me try this again. my engine wont stay running with maf sensor puluged in, if i unplug it it will idle fine,but still doesnt run right. and if i plug the maf sensor back in and unplug cam sensor it will idle idle fine,but i havent tried drivin it like that.and with both pluged in it runs like crap,it sputters,then dies.any ideas would be helpful.its a 91 sc auto. just got it and its my first one
 
"runs like crap, it sputters, then dies" at idle...

Pull the DTC's.

If you haven't disconnected the battery anytime after this problem started, DON'T do it now. Take a jumper wire and do the KOEO (Key On, Engine Off) procedure. With the key off, find the test connector on the passenger's side fender ('94-'95 SC). Pull the wire harness connector, and the single connector from the plastic cover. Looking at the wire harness connector from the front, with the short side down, insert the jumper into the bottom left connector. Insert the other end into the single connector (EEC ground).

Turn off everything, and
Turn the key on and listem for some relays to click, the radiator fan to start and stop while sitting in the driver's seat, watch for the "check engine light" to flash after radiator fan turns off for DTC's.

A normal non-erro condition set of flashes will look like this:
0 #1 #2 #3 #4
*--*-*--|*-*-*--*-*-*|--*--|*-*-*--*-*-*|
2 111 111 111 111 All Good
___________________________________________
111 111 214 214 Proglems
512 512
(-) = short pause
(--) = long pause
(*) = flashes
(|) = seporator

Any DTC's you get, post them here, if I can't help, somebody should be able to direct you further.

discipled1
 
i got this if i did it right
*--*--*--*-*-*-*-*-*--*-*-*-*-*--*-*--*--*--*-*-*-*-*-*--*-*-*-*-*--*--*--*--*--*--*--*
i didnt know where to put the seperators
 
jmfasc said:
i got this if i did it right
*--*--*--*-*-*-*-*-*--*-*-*-*-*--*-*--*--*--*-*-*-*-*-*--*-*-*-*-*--*--*--*--*--*--*--*
i didnt know where to put the seperators
the first flash was more like a blink
 
Note that you should determin for your year of vehical what the actual number of digits will be proper. For instance, on my '94 I get 3 digit number, and I believe that older cars may get only 2 digit codes??? Since I only know about my experience, you should consult a manual or perhaps enroll with www.alldatadiy.com for vehical specific information.

Dang, I'm sorry for posting to this and not getting back to it. I must have missed it. It's a wonder nobody else replied to it. I was going over some of my old posts looking for an explanation on how to pull the DTC's with a jumper wire, and here this was... Didn't mean to leave anyone hanging... :(

Yeah, reading the flashes can be difficult the first time. I remember when I first did it. I was very aprehensive to say the least. Basically, the first blip of flashes are scanner only info being sent out to a code reader (which you don't have). Ignor this initial "quick flash" as they go by too fast for the human eye to read. The next flash(es) will be for the engine code. Two flashes will indicate a 6 cyclinder engine. Now here is where you start reading the out put. You will be presented with a 3 digit number, and then that same number will repeat itself. This first number(s) are call "Hard Codes." Hard codes are more serious then "Soft Codes." To read the hard codes, watch the flashes and count their number. In morse code looking text here I'll try to provide an example of what a singel 3 digit hard code number would look like:

...-...-... repeated ...-...-...
(3 3 3) (3 3 3)

If you get 1 1 1 and 1 1 1 then everything is okay with the hard codes (none present).

Now, once the hard code number repeats, there will be a long pause, followed by a single blip, and then a long pause to indicate that hard code reading has ended and now the soft codes will be displayed. The soft codes are read just the same way as the hard codes. A 1 1 1 and 1 1 1 indicate all is well. You have just done a KOEO test proceedure.

I should have given the directions on how to jumper the test plug first, but here's how you jumper the service plug to kick the computer into diagnostics for OBDI:
On my car the test plug is located on the passenger side fender under the hood. With the Key Off, Pull both connectors out the the plastic cover. Get a piece of wire and attach two spade connectors to the ends. Incert one spade connector into the bottom left hole in the larger plug. By this I mean, when looking at the plug head on, and with the fewest number of hole under the row of the greater number of holes, incert the spade connector into the lower left hole. Now plug the other end of the jumper wire into the smaller connector (single wire) that was under the plastic cover next to the larger connector. You just grounded the test circuit of the EEC and it will now go into test mode when you turn on the key. Get behind steering wheel, and watch the MIL light as it will flash after turning on the key.

To do a KOER test. Turn off the engine after reading the codes, and wait 20 secondes. Start the engine and and wait for the last flash to flash. Then, turn the steering wheel a 1/4 of a turn and leave it. Depress the brake peddle, and cycle the OD switch on the transmission shifter if you have one. Note: if you depress the brake peddle before the last flash (the one that says depress the brake peddle), you will get a DTC of "depressed brake peddle not sensed." Ignor it other wise. The idle will increase, some relays will click, the radiator fan will come on and then turn off, and then any problems will be displayed in flashes. A 1 1 1 means everything checks out okay. Anything else is a DTC.

If you want, after the last flash of what ever the repeated number is, you can depress the gass peddle for a couple of secondes and rev the rpms up to say 3000 RPM's, and then let off. This will put the car into a cylinder balance test. If you get a 9 count flash, all good. Anything else is a DTC. After the flashes here, you can again press the gas peddle to repeat the weak cylinder test (cylinder balance test) with the amount of fuel to the injector being halved from the first test. You can do the test one more time initiating it the same way by depressing the gass peddle and letting up, and this time the fuel is reduced even more. The reason of repeating the test is to pin point a problem cylinder, and if the injector for that cylinder is responding properly. You should hear a noticable miss that increases with each seccecutive test. If you do not, then the injector may well be leaking or not functioning as designed. The test can also tell you if you have a weak cylinder that needs further inventigation (i.e. compresson testing etc.).

I hope this clears up the issue, and if I've got anything wrong her I appoligize for that, as I wrote this from memory, so anyone out there that does find a proble herein, please post a correction, or add to it for you year vehical.

thanks.
 
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