Hello everyone,

I report from the final steps of my rebuild journey... My 88 305 TPI.

I recently got my upgraded rear end back in, new brakes on all the way around, new goose neck gasket, new EGR solenoid, and new EGR temp switch, EGR was replaced around 1000 miles ago.

Imagine my surprise, when going to start my car, I find that I STILL have a code 32 after all these replacement parts (I thought for sure the switch or solenoid would do it)
I tested the valve to see if it held vacuum (It does) and to see if the diaphragm held (It did).

I am looking to have my new exhaust and cat installed next week, so right now I have a gutted (not me) open cat exhaust.

I read a few statements about not having enough back pressure from the exhaust.... I was wondering if that could be the issue? Or if there is something else I can check in the meantime.

The code pops up almost immediately after starting the car. Now I did replace all the hard line vacuum hoses I could access, it is possible I hooked up the hoses wrong to the solenoid.

Here are the parts I used to replace... Temp Switch and Solenoid
Which hose is supposed to hook up to the gold line? EGR or Vacuum?

Is this the right temp switch? I couldn't find any clarification if this was a normally open or closed unit.

I appreciate the help, I know this has been beaten to death before, I'm just looking for some inspiration or maybe something I missed.

Thanks!

 

Right temp switch, could always turn off the flag in the ecm

 

Well, I am buying my tuner sometime in July, these new tires + having my exhaust installed with SFC is gonna set me back a little bit.

Do you think having the open and gutted cat could cause the code? I mean, it's essentially an open header situation.

 

Did you verify if the egr was n or p backpressure when replacing?

 

No... When I replaced it I wasn't aware that there were two different models.

Which one is it supposed to be, and how would you verify?

 

It is most likely that the engine was originally equipped with a negative backpressure EGR, and that would be indicated by the letter "N" being stamped in the vacuum servo cover on the EGR.

If the error code is generated shortly after the engine is started, I would suspect either the EGR solenoid or the EGR temperature switch is not presenting the correct resistance to the ECM outputs. The EGR function check would only occur after the ECM is in closed loop and vehicle is operate under conditions which would operate the EGR, or in other words, at part-throttle cruise. This requires a low load factor (LV8), engine RPM above 1,200, throttle position above 6%, park/neutral safety switch (or clutch switch) open, cruise brake switch closed, intake air above 1°, etc.

 

Interesting, for a few days there wasn't any trouble or code at all.

Today it was pretty hot, and on the highway started hesitating... I knew what was coming. Shortly after the SEL came on.

I had to try and reset the codes quick, with my handy reader, but a whole slew of codes came on. Including 33, 34, 45 and one other.

I recently replaced every component related to MAF and EGR, as well as the o2 sensor last year.

After resetting the codes, I was able to take side streets to get to the shop I was bringing it to for Exhaust.

Any idea what could of caused this? Wont have car back till tomorrow.

 

Could be faulty ecm or even a rip in bellows, wiring or maf even if new.
trouble shoot 33 & 34 with fsm trouble tree

 

 

Hmmm, thanks for this, the MAF seems to be functioning properly... At least, it seems to be reading data properly.

I had to drive the car home from the exhaust shop last week, and the troubles started again, at the most inopportune time, I might add.

Without getting into too many details, during a highway trip, averaging around 75-80mph, I started getting some major hesitation again, to inevitable stalling after shifting out of gear.

This time I managed to get a picture of the codes I was getting.

They are as follows...

33: MAF Sensor High
32: EGR Diagnostic
43: ESC Failure
45: O2 Sensor Rich

So, my primary interest is in code 43.

I ordered a new knock sensor, and I plan on taking a look at my timing tomorrow.

Could the timing potentially affect all these other issues?

Why would the code only come on after highway driving for a certain amount of time? Bad sensor heating up and not reading properly?

It does make sense that this is what is stalling the car, as it does feel like a timing issue once it gets started, I mean it bogs bad.

At this point, I am creating a log for myself on the fixes.

I really don't want to try and replace any more parts for MAF/EGR at the moment. I have trouble believing the new O2 is bad, but I can test that after timing.

Once again, I have replaced the following parts:

EGR Valve
EGR Temp Switch
EGR Solenoid

MAF Sensor
MAF Relays
IAT Sensor
O2 Sensor
K&N Air Filters

Fuel Pump 255lph
K&N Fuel Filter

New Vacuum lines to everything visible, except the hard plastic line running into HVAC

New Cat and Exhaust...

When it runs great, it's a blast, though I do feel like I am missing some power. I will also mention, since I got the new fuel pump (might need adjustable fuel pressure regulator?) I have been putting 92 octane into the tank, hoping to clear out any extra crud.

I will report back tomorrow after timing adjustments, from there I am replacing the spark plugs.
I will also be looking at the TPS tomorrow, to see where that is set.
Friday I am getting my new knock sensor.

Is there anything else I should look at from here? How often does the actual ESC module die?
I was going to replace the pigtail for the MAF as well, as the clasp is broken, but it never shakes loose...

Oh, and for the record, the exhaust sounds great.

Thanks for helping me out. Hopefully y'all wont mind me using this as a notebook or journal of sorts.

 

Highway might of been forced knock test to throw esc error.
might wrap on the ecm
with a screw driver handle while running just to see if it acts up like a bad solder joint. Esc module is very reliable knock should ohm iirc 100k. Overly rich 45 kinda brings you back to 34

 

Hmmm

Definitely a lot to try. I just want a reliable running car, that's not too much to ask for is it? Lol

I hate being so close, yet still left in a vague bubble of possibilities.

So can we rule out the new fuel pump and the 92 octane fuel? I wouldn't be opposed to putting an adjustable regulator in, but I'd rather that be a last resort so I don't have to pull off the intake again.

 

If the ecm thinks it’s running rich and it’s stock no need for more fuel and a afpr.
exhaust leak by the o2, vacuum leak , bad ecm , Rip in bellows all some possibilities to look at.

 

Extra crud , car sit for some time ? Fuel pressure hold after a prime ?

 

Car only sat for about a year, but it really hasn't been running right since I bought it about 6 years ago.

The car seems to hold fuel pressure fine.

Could the exhaust leak be from the where the runners connect to the plenum? I had accidentally bent the gasket when I was reinstalling it a few weeks ago, didn't notice anything too obvious. . . How could one check for this?

As far as the vacuum goes, I've replaced almost every line possible, and the lines I couldn't access, held vacuum fine.

Please excuse my ignorance, but what are these bellows you're referring to?

 

How old is your ICM (ignition control module)? You may be fighting two (or more) separate problems. I know I got a code 32 after installing headers; Brian tuned that out for me. I then had the hesitation on the highway; felt like you turned off the key for a split second, then back on. Replaced ICM and problem fixed. As you're getting a code 43, that seems like a possible culprit. Lack of spark could then create a rich condition which could explain the code 45. Just my two cents...

 

Hmmm thats definitely something I'll add to the checklist. About 3 years ago I replaced the cap, coil, and ICM, but I dont believe I went ACDelco last time.

I've got a few things to try out over the weekend for sure.

 

Of course, you have checked the engine harness grounds at the rear of the intake/head, right? Since the various error codes are all related to the ECM analog ground, it might be sensible.

 

I've checked all im aware of.

In the past two days I've done spark plugs, timing, iac and a tps adjustment. For fun, I also double checked the connection to the solenoid itself.

After this, I reset my computer and took her for a drive.

I hazard to say this is the best the car has ever performed, and no codes after getting on the highway for about 20mins.

Huge change in acceleration and deceleration, feels very smooth.

However at idle, it wants to "lope" a little bit. I think that's the proper term.

I was planning on taking out and cleaning off the IAC to see if that makes a difference.

Thanks to everybody thus far on this journey!

 

So im a bit of a dunce. I had the vacuum lines attached to the egr solenoid wrong. I've also got my idle locked in around 900. No codes so far. Gonna try to drive it into work and hope for the best tomorrow.

Only thing I notice now is that I seem to be getting some knock at WOT. At least that is what the live data is telling me.

I got a new sensor and pigtail to replace in case I deduce its bad.

 

Well, strangely the issue persists.

This time it triggered during regular city driving.

Code 32 comes back to haunt me.

I got a screenshot of my live data before the code hit, and the EGR seems to be operating properly... I don't understand what the issue is. All I can think to do now, is replace the EGR valve again. Maybe someone can link me to the exact one they used?

If that doesn't work, I feel I will have to program the code away, as this is impeding on my enjoyment in an extreme fashion.



Does everything here look okay??

 

Someone may know solenoid resistance of egr solenoid.
the ecm doesn’t know if egr actually opens afaik just if solenoid is controlled.
looks ahair rich other than that don’t see a issue.

 

I am using the Corvette solenoid, I wonder if it has anything to do with the connection extender I made. It really shouldn't have that much of an impact i'd feel, just the two wires...

I am going to test for fuel pressure and check my injectors tonight or tomorrow night. Maybe I have an issue there.

Also gonna unplug and check ECM for anything loose.

 

7½ kg/s flow through the MAF? You neglected to mention that you installed a P&W Wasp Major in place of the SBC. At 4,360 cubic inches, that's about the only thing that is going to flow like that. I suspect your software has some issue.

As for the EGR solenoid, my records show a "good" one should be between 35-50Ω.

 

The gps I’ve seen false reading with universal scanners and some Bluetooth applications.
just ignored the false data.

 

I do use a bluetooth device...

It's called ALDL Scan on Android.

I have the equipment to hook up to my laptop though, what software would you guys suggest for more accurate data?
I plan on ohming everything out tonight.

Code 33 popped back up. My pigtail for the MAF had the clip broken off the connector since I bought it, gonna replace the pigtail too.

 

Tunerpro rt $32b adx is a good program

 

Awesome, thanks, I'll see if I can't get this loaded up after I get out of work.

 

Beating my head against the wall.

Code 32 on Startup, let's talk.

I replaced the Temperature Sensor for the EGR valve with a Corvette one. I extended the harness using a similar connector.

Is this the only thing that would cause an immediate (Within 30sec) Code 32 on COLD Startup?

I read that the 88 Vin F temp switch is normally open. Is the Corvette one normally open as well? Is it possible that I tightened the thing down too much?

I don't know what else to do with this freaking code... On the highway, when I don't have a code, I can see the EGR cycle fluctuate while driving, which tells me it's probably working?

Very frustrating.

 

Vette temp switch is the same. I minght have a extra one but not sure if it’s any good

 

Alright, here's an update.

I have just torn apart the top of my engine again to put in some new Bosch fuel injectors. After much stubbornness, they are in and seem to seal well.

In other news, I got the used Temp/Diagnostic Switch for the EGR from Tuned.

If I was doing the test correctly, the switch should ground out at a certain temperature, at least I read that on here somewhere.

Here is the odd thing, the new Corvette switch I installed seems to be in a Normally Closed/Grounded state. I got continuity right away connecting a prong of the multi meter to the "barrel"/switch and to the pigtail. I suppose it failed or is bad?

I proceeded to heat up the switch, and once I got it to a fairly hot temp, the continuity went away! Which would potentially explain why it (code 32) would go off randomly, and also appear at start up occasionally.

So as I mentioned earlier, the donor switch I received did NOT have continuity while cold, with the heat gun, I was able to get it to ground out at a high temperature.

Hopefully this switch from tuned saves me some trouble!

Thanks to everyone for the help.

 

Fingers crossed it’s the fix. I’m pretty sure the c4 temp switch is the same as f body jus a sort lead

 

Im thinking Its a lemon or it went bad somehow.

Had to get a new bolt kit so I'm waiting on those before final test

 

Pm me there’s a work around

 

I believe the corvette solenoid does not work in our cars. I had to return mine as it was backwards (energized/de-energized = closed/open) and I had to stick with my original one (which worked just fine). Also, what helped me was to put a T on the vacuum line to the EGR valve and ran a vacuum gauge to the interior so I could see when the EGR was valve holding vacuum and when it wasn't. If the EGR valve is holding vacuum, then the valve is almost certainly flowing EGR. If the valve is not holding vacuum, either you do not have enough backpressure or the solenoid is not opening to allow vacuum to the diaphragm in the EGR valve.

 

 

So, final update, I hope.

I replaced the EGR valve with a new one, went back to the stock throttle body, replaced the injectors, put in a old stock temp sensor, and after a long drive in the heat today, no codes!

Let's hope this is the end.

Thanks again for everything guys!