Engine question

Dryfter_09_19 · Post by **Dryfter_09_19** » Mon Jan 30, 2006 3:29 pm

My '85 has been a little bitchy lately and she gets all luggy around the 1,500 to 2,000 then smothes back out after i get below 1,500. (This is while i'm down shifting). One of my friends (who's in a mechanic class) says that it could be an ERG valve (or something like that) or it might be something to do with the wiring having a short.

Can anyone give me some insight into whats going on? I would like to know so I could fix it. But if I can't fix it I'll probably just send it to the shop.

Shaun41178(2) · Post by **Shaun41178(2)** » Mon Jan 30, 2006 10:56 pm

dont' think the egr valve would cause this.

4 banger? how is it above 2500 rpm?

Dryfter_09_19 · Post by **Dryfter_09_19** » Mon Jan 30, 2006 11:23 pm

It's fine once i get above or below 2,000 or 1,500 (respectively). I forgot to mention that everyonce in a while the car will randomly shut off and won't start. the RPM gauge spikes (while the engine is off), then the check engine light and battery light come on and i can start it up again (this is all while i'll be driving). Then my check engine light stays on till sometime when it decides to be normal.

Like I went out to my car this morning. started her up and it was fine. no check engine light, no "lag" when down shifting. I got to school and parked it. Came out around 11 and got in started it up and the check engine light was on and it was shitty through those RPMs.

Shaun41178(2) · Post by **Shaun41178(2)** » Mon Jan 30, 2006 11:34 pm

ok so what codes is it giving you then?

p8ntman442 · Post by **p8ntman442** » Mon Jan 30, 2006 11:42 pm

sounds like a coil on its way our, what do you think shaun?

Dryfter_09_19 · Post by **Dryfter_09_19** » Mon Mar 20, 2006 3:53 pm

Well, I would check for the codes, but I don't know where the port is for the scanner. I've looked all over and I don't see anything that looks like what I need.

TurboGT · Post by **TurboGT** » Mon Mar 20, 2006 4:05 pm

You have to take off the pannel that covers the cigret lighter. It is behind the pannel to the right if the cig. lighter. You need to jump pins a and b together and then turn the key on and watch the check engine light flash. It should flash code 12 three times and then any codes you have three time each and then it will start flashing code 12 again when it is done.

Good luck

Dryfter_09_19 · Post by **Dryfter_09_19** » Mon Mar 20, 2006 4:13 pm

whats code 12?

Series8217 · Post by **Series8217** » Mon Mar 20, 2006 4:15 pm

That means you're in code check mode

It basically tells you that the ECM is working well enough to give you codes if there are any.
If all you see is code 12 flashed repeatedly, no codes have been stored...

Mach10 · Post by **Mach10** » Mon Mar 20, 2006 4:49 pm

Ignition problem...

Any kind of funkiness can usually be traced to that god-forsaken abortion that GM chose to call an Ignition Module.

Random stalling with the tach goofing up is usually the module starting to go TU.

Other than that, check all the connections around the coil and distributor. Backtrace the wiring also to the fusible links, as I've seen some pretty twisted shit happen from bad fusible links.

Dryfter_09_19 · Post by **Dryfter_09_19** » Mon Mar 20, 2006 10:33 pm

Ok, I don't think this is very good but.

Here are the codes.
13, 24, 33, 35, 42

Thanks for your help!

MNFatz · Post by **MNFatz** » Mon Mar 20, 2006 10:50 pm

Code 13: Oxygen sensor circuit
Code 24: VSS
Code 33: MAP sensor
Code 35: IAC
Code 42: EST.

Yahtzee! That's quite the laundry list.

Check the TPS and make sure it doesn't skip or have any dead spots in it. Use an ohmmeter and make sure the resistance is proportional to the position of the lever on the sensor.

I've you've absolutely ruled out vaccuum leaks, that's where I would start.

Edit: screw that. vaccuum leaks aren't causing that problem.

p8ntman442 · Post by **p8ntman442** » Mon Mar 20, 2006 10:50 pm

we need an engine code sticky in this section shaun.

whipped · Post by **whipped** » Mon Mar 20, 2006 11:48 pm

coil or module.

Aside from the fact that everything else is broken too.......

Shaun41178(2) · Post by **Shaun41178(2)** » Tue Mar 21, 2006 12:01 am

My suggestion?

Jack up the radiator cap and drive a new car under it.

I think a code list is a good suggestion. I will do it, just not right now.

Mach10 · Post by **Mach10** » Tue Mar 21, 2006 12:25 pm

Bear in mind that one bad sensor can throw expected values off of other sensors.

It's a place to start, anyway.

Test each 'coded item with a multimeter, and you can get a good idea of what's going on.

Sounds like the bastard is running badly in LIMPHOME, which means the timing and mixtures will be boned.

Here's some basic tests to test for sheer boned-ness tests:

O2: Disconnect the O2 Sensor. Drive the car around the block for at least 10 minutes, until the car is up to temperature. Then, while trying hard not to burn yourself, connect one end of the multimeter to engine ground, and the other to the O2 Lead wire. At idle, your voltage should be swinging around merrily at 0.5-0.7v. When you blip the throttle, the voltage should peg over to (god, I *ALWAYS* get this backwards) 0.9v. or 0.4v... Damnit... One of the two. Long and short of it is that while you play with the throttle, the voltage should be all over the place. If it sits sluggishly at a single voltage, it's boned.

VSS: Make sure it's connected. Jack up the rear of the car, disconnect the sensor, and check the resistance (2000ohms, iirc) across both wires. Start the car and have someone put it in gear and free-wheel for a few moments. You should be getting alternating high-and-low resistance values.

Map sensor: With car running, run multimeter (set to read 1-5v) in parallel to pin # 2 and to ground. At idle, the voltage should be constant, and spike up to 5v if you open the throttle all the way. Change should be FAST. If it's sluggish, the map is boned.

IAC? Fucked if I know how to test a stepper motor. Listen for it whirring when you turn the ignition on but don't start the car.

EST: THat's your spark module. Pull the bastard out and get it tested at your friendly local Fellatio Barn (aka part store)

Honestly, with that many codes, I'd suspect you've got some bad grounds or bad reference wires coming off the ECM.

With the exception of the O2, all of those there need a steady 5v reference from the ECM. Check the wire look for burns, breaks, shorts. Make sure that the reesistance to ground from the ECM ground is 5ohms or less.

You've got some work ahead of ya.

p8ntman442 · Post by **p8ntman442** » Tue Mar 21, 2006 2:45 pm

Mach10 wrote:IAC? Fucked if I know how to test a stepper motor. Listen for it whirring when you turn the ignition on but don't start the car.

To test it, remove it, and leave it plugged in. Have someone turn the key to the on position, the car shoudl be in aldl mode. If it is working, it will turn the pintle, if not, it will hum or buzz, and turn back and forth. Be careful, if its working, it will shoot the pin off the end and you could loose parts or an eye if your an idiot.

Mach10 · Post by **Mach10** » Tue Mar 21, 2006 2:54 pm

Cool! I learned something today!

I don't know what it's like internally... But there should be a way to test ANY EFI component with nothing but a multimeter and a constant 5v source...

I wish I knew more.

Pyrthian · Post by **Pyrthian** » Tue Mar 21, 2006 3:38 pm

I'm not familear with the 4-banger, but...
I'm gonna start with the TPS sensor. it's probably worn off all the contact at the bottom end. the ECM is seeing zero throttle, even tho the throttle is opening, so it doesnt make the proper timing & fuel adjustments until it gets to a clean spot on the TPS. also, a sticky old MAP sensor will do this.
also, like above, ignition is another area to look at. bad spark plug cables allowing cross fire, or just plain old spark leak. getting ALDL hooked up will help alot in finding whats wrong.
blaming EGR is a favorite of people who aren't sure whats wrong. you can easily take the EGR out of the equation by taking off the vacuum line to the EGR mushroom.

Mach10 · Post by **Mach10** » Tue Mar 21, 2006 4:38 pm

Oh, its a 4banger? I didn't catch that.

Yanking the EGR may cause it to idle-hunt (up-down-up-down) but it won't usually make it miss or stumble unless it's jammed wide open.

It's 2 easy bolts to get the valve off... Make sure you don't lose the metering ring. Check that the valve seat is reasonably clean, and that the valve moves up and down freely. Next, push the valve in, wet your finger (spit on it) and cover the vacuum port. Let go of the pintle, and make sure it doesn't sink. It'll move a bit to take up vacuum, but it should stop WELL before fully closed.

I'm with Pyrthian... Probably not the EGR... but it's something to check, for sure.