trouble codes

[92GaEnthusiast]

My check engine light has been on ever since I swapped out my sohc for a brand new dohc, and I ran the self diagnostics on it, and I got back the following trouble codes:

Code 34 - which I have been told is the MAP sensor code, he told me to check my vaccum hoses and if that doesn't fix it, replace the map sensor.

I also get code 26, which I have researched is tied into the transmission, but everyone who has had problems with it has been from automatics. Mine is a manual 5 speed transmission, and I am getting a code 26. I have no idea what this code is, neither did the guy at the auto parts store.

If you could give me some insight, I would really appreciate it! Thanks alot.

[carlover626]

What engine are you talking about? 2.4 I-4, 3100 V-6?

I have never heard of a code 34? Are you talking P0340?

[92GaEnthusiast]

I'm talking about the quad4, 2.3l from a 92. It give code 34, which is the map sensor error code), but I am not sure what code 26 is.

[rixGAphx]

Originally posted by carlover626
What engine are you talking about? 2.4 I-4, 3100 V-6?

I have never heard of a code 34? Are you talking P0340? He's talking about a 1992 car, and engines with one (or two) overhead cams (SOHC and DOHC).
P0xxx codes are OBD-II 'P'owertrain codes. OBD-II came along in '96.
3100's came along in '94; prior to that, there was the 3.3 liter V6. No GA V6 engine has ever had overhead cams, single or double; they have all been cam-in-block, known as 'OHV' (ovehead valve.

Pre-'96 cars (pre-'94 GA's) came with a crude engine computer system, called OBD-I (On-Board Diagnostics, Generation 1).
You didn't need a scan tool to read the codes, the dashboard 'Check Engine' light flashed-out two-digit code numbers and you sat there and counted flashes.
* On GM vehicles, you jumpered a couple pin sockets with a paperclip to commence the flashing.
* On Chryco's, you turned the ignition 'off-on' three times rapidly to commence the flashing.
* I don't know what Fords and foreign vehicles did.
Then you looked-up your vehicle-specific code, such as 34 or 26, on a special list of codes.

Our Haynes '85-'98 GA manual says that:
26 = Quad Driver Circuit.
34 = Manifold Absolute Pressure (MAP)sensor circuit - signal voltage low.
OR
34 = Mass Air Flow (MAF) sensor circuit - low frequency.

I wouldn't know a 'quad driver' from a nine-iron.
But I understand it's a device internal to the car's computer.

I hope this helps,
-Rick

[92GaEnthusiast]

So that means the ECM is bad? I sort of suspected that it was. any way to fix the other solution? You think that could be caused from a bad ecm ?

[rixGAphx]

Originally posted by 92GaEnthusiast
So that means the ECM is bad? I sort of suspected that it was. any way to fix the other solution? You think that could be caused from a bad ecm ? Well, I think I would just clear the codes, and see if they come back.

Beyond the CEL and the codes themselves, you haven't indicated any problems whatsoever with the car or engine.
Is it running well?
Strong, smooth, proper temprature?
Decent fuel consumption?

Personally, I can't think of a good reason why a dumb, 15-yr old engine computer made for a single-cam engine (with 2-valves-per-cylinder) would work all with a high-performance DOHC 4-valve engine.
It don't think the ECM is necessarily 'bad', it was just intended for a *slightly* different engine, and it is *slightly* confused by the data it is now receiving.
That computer is really quite stupid and has limited memory into which 'defaults' could be hard-programmed.
When it was designed, Intel hadn't even released the 486 chip, and the Pentium was unheard-of.
But we have just exceeded my understanding of computers, so make your own judgement on this.

-Rick

[92GaEnthusiast]

nah, the dohc and sohc computer are the same, only difference is the chip, which was replaced for the dohc.

Every so often, the car misfires, and idles high. not to mentio the speedo stops working and once in a while the temp gauge goes to overheating, even though the car isn't.

[rixGAphx]

Originally posted by 92GaEnthusiast
nah, the dohc and sohc computer are the same, only difference is the chip, which was replaced for the dohc.Well, the chip is the entire brains of any computer.
Though the box that contains it may be the same, to my mind that IS a 'different computer.'

Anyhow, you've established that the 'puter isn't the problem.

Every so often, the car misfires, and idles high.
Not to mention the speedo stops working and once in a while the temp gauge goes to overheating, even though the car isn't. Does the engine 'idle high' at all times, or only "every so often?"
If it always or often idles high, is this when the engine is:
* Cold, or
* At operating temperature, or
* Both; or
* No discernible correlation?

I would look for a vacuum leak.
* * *
If the speedo just 'stops' intemittently, look for faulty wiring from the Vehicle Speed Sensor (located at the bottom of the tranny output near the differential).

Ame with the coolant temperature sensor, though I don't know where it is on your engine.

And as with any electrical problem with a GA, verify that the battery cables and the grounds are all in order.
GA's do strange things when the electrical power isn't just right.

Good luck,
-Rick

[92GaEnthusiast]

It seems to me that it idles a little higher after a cold start, but it also does it at random times.

As for the strange speedo problem, I thought that would be more related to the ECM (as the vss is connected into the ecm). I've been reading articles and alot of people are pointing toward all the problems I have, and it results in an ECM problem. I may have surged it by not removing the battery before I un-installed it to replace the memcal chip.

I was going to replace the map sensor and maf sensor, but I seen the price of both of them, and it's a little high to spend on a 'wim'. I read the haynes manual on how to troubleshoot both, and I'm going to give them a try today to test them.

[rixGAphx]

Originally posted by 92GaEnthusiast
It seems to me that it idles a little higher after a cold start, but it also does it at random times.With a 15-yr old car, it wouldn't hurt to thoroughly-check all the vacuum connections, mebbe even replace all the black-rubber nipples that are prolly cracked and leaking slightly.
Minor leaks can appear/disappear, depending on the temperature/suppleness of the rubber.

As for the strange speedo problem, I thought that would be more related to the ECM (as the vss is connected into the ecm).
I've been reading articles and alot of people are pointing toward all the problems I have, and it results in an ECM problem.
I may have surged it by not removing the battery before I un-installed it to replace the memcal chip.One of our most-recent posters just had a major problem witha VSS wire, so that's what rang my bell on that issue.
With a car of yours age, who knows what sh!t it has experienced on its underside; certainly possible for a branch or other road debris to have snagged a wire.

'Twould be shame to spend $80 on an e-bay ECM only to find the problem was a frayed wire requiring a 59-cent repair.

I was going to replace the map sensor and maf sensor, but I seen the price of both of them, and it's a little high to spend on a 'wim'.
I read the haynes manual on how to troubleshoot both, and I'm going to give them a try today to test them. Ah, you're obviously a frugal Scotsman :D :D

Yeah, they're just dumb-ol' electrical devices, certainly capable of being tested.
A lot wiser than just throwing money at the problem.

Good luck,
-Rick

[92GaEnthusiast]

Thing is, when he new motor was put in, EVERY hose in the engine compartment was replaced, both radiator and air hoses.

It could be as simple as the a/c compressor hose being removed, because it broke. I don't know if that ties into the vaccuum problem or not. As far as I knew, it didn't tie into the engine at all, but it could. (It's the metal hose that connects to the back of the a/c compressor, that has the return and all that for the a/c, and connects to the bottom of the car)

Also, I wanted to ask. if I reset the ecm to get the check engine light off, as long as the problem is still there will the light come back on? I am low on funds right now to purchase a whole bunch of stuff to troubleshoot it, so i'm going to do a couple tests, and if everything comes back alright i'm going to clear the codes for now. Will they come back?

[rixGAphx]

When an OBD-I ECM, such as that in your '92, has the codes 'cleared', they are permanently erased.
No record remains (which was one of the reasons to change to the more-sophistacated OBD-II).

When the ECM detects the problems again (if the causes are still there), then the CEL will again be illuminated.
* * *

You're right, the AC refrigerant hoses do not affect the engine performance.

But the AC dash controls are vacuum-operated.
So though the underhood hoses and tubing were replaced, you could still have a vacuum leak in the tubing under the dash, or at the HVAC control panel, or at one of the little vac motors that opens/closes the ductwork.

[92GaEnthusiast]

none of those were touched, and the light wasn't on before the motor was replaced. It started after the new motor was put in.

[Matt95GT]

I'd triple check for vacuum leaks. Code 34 would easily be caused that way. Might want to hook up a vac gauge temporarily to see what's going on.

Didn't you use an earlier Quad 4 for the swap? Where did the MAP sensor come from? It needs to match the PCM calibration... a different MAP sensor could cause it. The early Quad 4 MAP sensors seem to be different.

Don't worry about a MAF... you don't have one. I wouldn't worry about the Quad driver code either... in fact that may disappear once the other is resolved.

[92GaEnthusiast]

I used the same MAP sensor. Looking up the part numbers between the 92 sohc and the 90 dohc came up with the exact same part. No idea what a vacuum gauge is, nor where to get one or how to use it.

Just to double check, let me make sure I got all the vac hoses.

There is a small one coming from the map sensor to the intake manifold, there is one coming from the air box into the oil/air seperator, there is one going into the throttle body coming from the air box (the big duct), there is on going from the oil to air seperator to the timing chain cover.

Am I missing any places? Seems that i've gotten them all, as far as where air travels.

[Matt95GT]

Originally posted by 92GaEnthusiast
I used the same MAP sensor. Looking up the part numbers between the 92 sohc and the 90 dohc came up with the exact same part. No idea what a vacuum gauge is, nor where to get one or how to use it.

Just to double check, let me make sure I got all the vac hoses.

There is a small one coming from the map sensor to the intake manifold, there is one coming from the air box into the oil/air seperator, there is one going into the throttle body coming from the air box (the big duct), there is on going from the oil to air seperator to the timing chain cover.

Am I missing any places? Seems that i've gotten them all, as far as where air travels.

Actually you'll want to use the MAP sensor part # for the year the memcal is meant for... use that year to cross-reference the one you have installed.

A vac gauge connects to a vacuum line on the intake manifold... it will show your vac pressure. If there is a vac leak, it will show. Besides the vac and boost/vac aux gauges for mounting in a pilar, there are test gauges for temporary connection that mechanics use.

You're missing a few... brake booster, fuel pressure regulator, accessory vacuum (TB to vac accumulator "egg" under battery, then to HVAC and cruise control), EVAP purge (runs to EVAP purge solenoid near oil separator, then to EVAP canister under coolant overflow tank) As for the oil separator tubes... there's 4: timing chain housing, drain back to oil pan, vac to intake manifold, and the one to the intake tubing near air box.

[92GaEnthusiast]

brake booster wasn't touched at all, hoses weren't removed, so I can tell you that one is fine. Fuel pressure regulator wasn't removed either, although the fuel rail was removed from the throttle body, and put back on. As far as the throttle body hoses, they are all connected fine.

The EVAP canister hooks up to the a/c doesn't it? Would that missing A/C hose give a check engine light for a vacuum leak? That metal a/c line that bolts onto the back of the a/c compressor is missing as it broke trying to remove it. Wonder if that would cause the light.

This is what the hose looks like that was removed:

http://info.rockauto.com/FourSeasons/FourSeasonsDetail.html?56407.jpg

[Matt95GT]

Don't assume anything... actually check the hoses and lines, even if they were never removed. All of my vac leak issues were on lines I never messed with... rubber deteriorates, and the hard plastic vac capillary tubing is known to get brittle with age. A leak doesn't necessarily have to be conveniently located near the TB... Murphy's law usually wins and the leak will be in the most difficult spot to get to.

No, the EVAP system is not connected or related to the AC. EVAP is connected to the fuel system.

No, you wouldn't get a SES light, the AC compressor simply won't engage since there wouldn't be enough pressure detected by the sensor.

[92GaEnthusiast]

Hmm, so what do you recommend for checking them? Just check to make sure all of the hoses are secured tightly, and that none of the hoses are broken/brittle? As i said all of the hoses engine was were completely replaced when the new motor was put in, but it could very easily be that some of them are loose.

[rixGAphx]

Originally posted by 92GaEnthusiast
Hmm, so what do you recommend for checking them? You can do a DIY inspection for vac leaks:
* There's a decal on the passenger strut tower for the Evaporative Emissions System Components (or similar title).
Your leak prolly isn't in this system, since this system is monitored by the computer and will often throw codes when it leaks.
* Your 'Vacuum System' is the other devices, tubes and connections on the top of the Upper Intake Manifold; they serve the Cruise Control, the HVAC controls, and the powerbrake booster.
Procedure:
* Visually-inspect the system with the engine 'off'; replace cracked or melted tubing, and reconnect loose fittings.
* Get a spray can of "Winter Starting Fluid" from AutoZone/Checker/Kmart/etc., about $4.
* Warm the engine, and open the hood.
CAREFUL!!! The spinning belt and pulleys are dangerous!
* Spray a little fluid at each device, tube, and connection.
* At a leak, the sprayed fluid will be sucked-in, causing the rough-idling engine to smooth-out and rise in rpm for a couple seconds.

Good luck,
-Rick

[92GaEnthusiast]

I forgot to mention, to test my fan I unplugged my MAP sensor with the engine running, and the ses light came on. I plugged the map sensor back in, but was wondering if that would cause the ses light to come on and stay on until it was cleared, or if it clears itself when the system gets fixed.

I forgot all about that!

[carlover626]

I believe unplugging the Neg. Batt. cable for 10-15 minutes will clear the codes...at least that was true on my 97.

[Matt95GT]

Originally posted by 92GaEnthusiast
I forgot to mention, to test my fan I unplugged my MAP sensor with the engine running, and the ses light came on. I plugged the map sensor back in, but was wondering if that would cause the ses light to come on and stay on until it was cleared, or if it clears itself when the system gets fixed.

I forgot all about that!

Bingo, that will do it.

[92GaEnthusiast]

Okay, I reset my codes and it appears they are still coming back. I had it disconnected for about 5 minutes while I put on my air filter.

I am on my way to my mom and dads to show them my new wii, I am going to disconnect the cable and leave it disconnected while i'm there (which should be a good two hours), and than I will see if it's still there!