Having problems.

[usarmytanker2006]

I have a93 z28 that I put a caprice short block in. Due to my tight budget I have to leave the caprice cam in it. I've replaced the optispark with a cheap cardon once again do to budget. I have 3 codes right now code 25 41 65. I've already replaced the o2 sensor as well as iat both temp sensors spark plugs. I have removed the air pump and the tube that goes to the headers. I have hooker long tubes ory that's about it. I've checked plug wires they are all right. Once it goes in open loop the ses light comes on the idle get low and choppy and it sounds like its sucking air real bad. I've been talking to popo8 and we want more input.



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[popo8]

I explained Im only one person.. and asking for help from the forum will yeild more "brain power" and experience.

I wanna clarify something... U mean when the car goes into CLOSED loop it acts up...right?

LTXtech.com is my DRUG!

[usarmytanker2006]

Ya that's what I ment lol..

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[popo8]

ok... and my original thought was 02s since the comp relies on them after goin to closed loop. This is where im hopin others will weigh in.

LTXtech.com is my DRUG!

[shippy8907]

Well doesn't closed loop rely on the O2 sensors for input? Sounds like there is an issue in the harness somewhere then if you replaced the sensors.

[usarmytanker2006]

I replaced just the right bank cuz that's the code im getting.

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[Injuneer]

Do you still have the 93's single-wire O2 sensors, or have you converted to 4-wire heated sensors to compensate for the problem of keeping the sensor hot enough with long tubes?

Have you cleared the codes to see which one comes back first and turns on the SES light? A couple of them may be stored codes.

[usarmytanker2006]

I didn't know I had to go to 4 wire.. So the single wires won't work with long tubes? Yes I have the 3 codes I posted keep coming back. I think the opti code 41 is stored.

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[JCzNova]

You pulled the EGR tube? Did you do block off plates on the back of the intake?

Still running your F-body tune on the B-body cammed engine?

[Injuneer]

You don't "have to", but you need to be aware it can be a problem. The ECM may drop out of closed loop if the sensor doesn't stay hot enough. But I asked because it's possible you have a wiring problem, and I needed to know how you have them wired.

If you cleared the codes and all 3 keep coming back none of them are stored. DTC 41 is for an ICM open circuit, not the Opti.

[JCzNova]

I didn't know I had to go to 4 wire.. So the single wires won't work with long tubes? Yes I have the 3 codes I posted keep coming back. I think the opti code 41 is stored.

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He means historically with going to long tubes and having the non-heated O2's people have had problems with them not being able to "warm up" enough.

@Fastbird (http://ltxtech.com/forums/member.php?u=2) (sponsor here) makes the wiring kit to ease swapping to heated O2's.

http://www.fastbirdperf.com/93-97F-Body/93HeatedO2.htm

[usarmytanker2006]

Yes its still the stock Camaro tune.

So there's a problem with the icm? My manual says 41 is open signal circuit from distributor

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[usarmytanker2006]

And yes I put the block off plate on.

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[Injuneer]

1993 FACTORY manual, page 6E3-A-70 5.7L (VIN P) Driveability and Emissions:

DTC 41

Ignition Control Circuit
{Open or Shorted Circuit)
5.7L (VIN P) "F" Cal Line (MFI)

DTC 41 will set if:
-Voltage on CKT 423 exceeds 4.6V
-Engine speed is less than 1500 RPM


CKT 423 is the white wire from pin A12 of the ECM to pin B on the ICM.

In summary, the Opti does not communicate directly with the ICM. The Opti pulse signals go to the ECM to establish where the crankshaft and camshaft are in rotational degrees (based solely on cam position). The ECM uses these signals to determine the individual ignition timing for each cylinder. The ECM sends a pulse signal to the ICM, telling it when to fire the coil.

If the Opti is not producing the cam position info, the ECM will set DTC 16 (low resolution pulse) and/or DTC 36 (high resolution pulse). Do you have those codes?

If the ECM is sending the pulse signal to the ICM, the voltage on CKT 423 should range between 0.5 - 4.5V.

If you would like a copy of the referenced DTC 41 document, including the diagnostic tree to help in testing the ICM, I can e-mail you a .pdf copy.

[Injuneer]

For DTC 25 - Bank 2 O2 sensor Circuit / Rich Exhaust Indicated

Code sets when O2 sensor signal voltage remains above 700 milliVolts for 50 seconds, throttle angle greater than 4%, system operating in closed loop.

Can be caused by:
-Fuel pressure too high
-Rich injector
-Leaking injector
-Fuel contaminated by oil (do you have oil in the line from the passenger valve cover to the throttle body, or in the throttle body?)
-EVAP canister purge rich due to canister saturation with fuel.
-MAP sensor indicating lower than normal vacuum
-Throttle position sensor intermittent output indicating the engine is acceleratiing
-EGR staying open

If you had a heated O2 sensor, another possible cause would be the O2 thimble sensor wire shorted to the 12V sensor heater wiring. But that can't happen with a 1-wire sensor.

Again, if you want a copy of the DTC 65 description from the 93 factory manual, with diagnostic tree, let me know.

[usarmytanker2006]

Injuneer I pmed u forgot my email address lol. Is usarmytanker2006@gmail.com

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[Injuneer]

.pdf file sent.

[usarmytanker2006]

Got it if I can get a break in the rain I'll check it. Witch pcm plug is "a"

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[usarmytanker2006]

Ok I have bat voltage at terminal a on the icm connector. And bat voltage with ecm plug a unhooked and key on. If I did this right that mean bad icm correct

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[usarmytanker2006]

I replaced the icm seems to be better but still getting code 26 not 25. And it lowering the idle and running choppy

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[popo8]

Have you CLEARED the codes? If not, You need to clear the codes... and drive it, and let it set fresh codes that are not being held in memory.

lets see what that yields...

[donfrye]

http://www.camaroz28.com/forums/lt1-based-engine-tech-9/dtc-26-a-314727/

AIR, EGR, or EVAP

If EGR is removed, it's logical it would be kicking that code, correct?

Injuneer should be able to jump all over this one as he's seen it a thousand times on other sites.

[popo8]

http://www.camaroz28.com/forums/lt1-based-engine-tech-9/dtc-26-a-314727/

AIR, EGR, or EVAP

If EGR is removed, it's logical it would be kicking that code, correct?

Injuneer should be able to jump all over this one as he's seen it a thousand times on other sites.

He is prob one of our MOST KNOWLEDGEABLE LTX members here....

[usarmytanker2006]

Egr is still on just not the air pump I have no ports on headers. When the rpm hits 3k it seems normal but when I give it gas off idle it pops and sputters and dosnt pick up rpm till almost wot

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[usarmytanker2006]

When I unplug the iat it idles fine

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[usarmytanker2006]

Yes I've cleared the codes everytime I try something. Im starting to think the pcm is bad

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[Injuneer]

If you have the EGR and EVAP solenoids connected, a solenoid could still be bad. Pull the harness connector off each solenoid, and measure the resistance of the solenoid. I think it's in the range of 15 - 30 ohms. What you don't want to see it an infinite resistance (burned out coil) or near 0 resistance (internal short). Hard to check the wires to the solenoids, other than the fuse (same fuse for EGR and EVAP). But both systems only operate intermittently. Fuse supplies 12V, ECM supplies the ground. Make sure you have 12V at the brown wire in each connector. No way to check the ground without a Tech-1 or -2.

For the AIR pump, the ECM has no way to know if the pump is connected, working, etc. Check the fuse for the AIR pump. As long as the fuse is good, you shouldn't get a code for the pump. The ECM is monitoring the relay, not the pump. You have to have a good fuse and a good relay.

[usarmytanker2006]

I put a new evap solenoid on it. Now I do have a quarter tank of gas missing. Would a saturated canister cause all this?

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[Injuneer]

The canister can saturate with fuel if you repeatedly over-fill the tank.

[usarmytanker2006]

The egr solenoid is at 30. Evap is 28

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[usarmytanker2006]

Fuse is good. Relay was 84 ohms from 85 to 86 terminal

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[Injuneer]

Should be OK.

[usarmytanker2006]

Now what? I have no idea

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[Injuneer]

Did you check the volts on the brown wires?

[usarmytanker2006]

No I didn't

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