Stumbling at 20% load? Found solution.

[Dojo2000]

<blockquote>quote:</font><hr>Originally posted by Ironman24:


If your EGR valve is sticking then it will throw hot air in the intake and cause a stumble under load, usually around 2-3K. I had this problem a long time ago, thought it was spark but found out there was a recall on the EGR units because of the sticking valve. Maybe 20% load is when the computer opens the EGR valve up. It's usually under cruise with load, never at WOT or high rpms.<hr></blockquote>

Lets say this is the problem, what kind of misfire readings would I be getting from OBD II? I've been watching these for each cylinder, but I can't make heads or tails of the readings. One cylinder shows around +150 all the time, while all the others show between 0 and -6. I don't have a clue what to look for.

[Dojo2000]

http://www.fbody.com/members/Dojo2000/logfiles/

finally found somewhere to host these files. If I remember correctly 4,5,and 6 were logged when it was stumbling. Could anybody take time out of thier busy schedule and look over these?

[Dojo2000]

Its 3 AM and I'm pissed. I'm such a f*ckin idiot [img]graemlins/dunce.gif[/img] I was looking over my log files and I noticed my four codes again; P0102, P1406, P1651,and P1652 NOT P1561 and P1562!!!! In OBD 2 it doesn't give a description for these two codes so I always overlooked the switched digits [img]graemlins/dunce.gif[/img] . BUT 1561 & 1562 are the codes the Autozone ( :rolleyes: ) guy wrote down for me. :mad:

Then I stumbled onto this list of codes in the archives.
P1651 Fan 1 Relay Control Circuit
P1652 Powertrain Induced Chassis Pitch Output Circuit
First code is obviously becuase of my manual fan switch. Second is a mystery

[ July 25, 2002: Message edited by: Dojo2000 ]</p>

[Dojo2000]

Now I've got some information that P1652 is Fan 2 Relay Control Circuit so now I guess I can ignore that code too.

[Ironman24]

There is an easy fix to this IF it's the problem. Go get you a thin sheet of aluminum roof flashing. Take the EGR valve off the mount, draw the gasket pattern on the aluminum and cut out a piece to block off the EGR. If in fact the EGR is sticking open and dumping exhaust in your intake that piece of aluminum will keep it out of there. But you will still get a EGR code, just not the stumble.

<blockquote>quote:</font><hr>Originally posted by Dojo2000:


Lets say this is the problem, what kind of misfire readings would I be getting from OBD II? I've been watching these for each cylinder, but I can't make heads or tails of the readings. One cylinder shows around +150 all the time, while all the others show between 0 and -6. I don't have a clue what to look for.<hr></blockquote>

[Fat_kid_in_little_camaro]

Try replacing All of the plugs and All of the wires before doing all that hard stuff (or do I maybe have it backwards??) well, it was easy for me. got soemone to change mine for 40 bucks. May have been a ripoff, but I didn't have to deal with it, and I didn't have to pay some garage 120 bucks to do it! [img]smile.gif[/img]

[Dojo2000]

Another update: changed all the coils, DID NOT help. :mad:

Can't change the plugs till someone answers my post about which plug wires work best with tubular manifolds.
http://www.camarov6.com/ubb/ultimate...c&f=1&t=007163

[Dojo2000]

[img]graemlins/fluffy.gif[/img]
When someone like Ironman24 or Magnus gives you advice, you really need to take it [img]graemlins/dunce.gif[/img]
Guys it could be none other than the EGR valve. I sat down and I thought about it:

Car starts up fine -&gt; it wouldn't if the plugs were fouled

Runs fine right after start up -&gt; it wouldn't if the plugs were fouled, and the wires were bad

After about 5 min of driving it starts to stumble when I accelerate -&gt; cause the engine and exhaust gas heat up

Changing coils didn't help -&gt; heated soaked coils weren't the ploblem

As the engine (and exhaust gas) heat up the stumbling gets worse -&gt; if EGR valve is stuck open car will stumble (just what Ironman24 said [img]tongue.gif[/img] )

Thanks man, I should have listened in the first place. I'm gonna make a block-off plate tomorrow to test it. What do I do about the exhaust side of the EGR system? block it off too? leave it alone? unplug EGR?

[Wht_n_blk_camaro]

Hey Dojo,
If that doesnt work, have you ever thought that yout catalytic converter might be clogged. When it gets hot and builds up pressure it's blowing out harder, and a clogged cat wont let the extra air out. That is why it bogs @ 20% load. Just some friendly advice.

[Dojo2000]

<blockquote>quote:</font><hr>Originally posted by Wht_n_blk_camaro:
Hey Dojo,
If that doesnt work, have you ever thought that yout catalytic converter might be clogged. When it gets hot and builds up pressure it's blowing out harder, and a clogged cat wont let the extra air out. That is why it bogs @ 20% load. Just some friendly advice.<hr></blockquote>

hmmm, also deals with exhaust gas. Haven't had any codes or bad fuel economy but I'll keep that in mind, thanks.

[Ironman24]

<blockquote>quote:</font><hr>Originally posted by Dojo2000:

Thanks man, I should have listened in the first place. I'm gonna make a block-off plate tomorrow to test it. What do I do about the exhaust side of the EGR system? block it off too? leave it alone? unplug EGR?<hr></blockquote>

I figured it was a easy test, possible fix, and also a mod at the same time. ;) Leave the EGR plugged up, the computer won't know there is a block off plate in there. All you need is that piece of aluminum underneath the EGR and it will keep the exhaust from going through.

[Dojo2000]

:mad:
Its been a while since my last update, but as it stand now, I still have the stumbling problem.
EGR valve was faulty, but that wasn't causing my stumbling. Made a block off plate on the intake manifold out of Delrin, and just unpluged the EGR valve. Didn't help. So I took it to the dealership :( They said I needed a new EGR valve ( :rolleyes: $34 to tell me what I already knew) I told them this wouldn't solve my problem, but they couldn't find anything else wrong.( probably didn't even look :rolleyes: ) I even told them to check all my plugs. Bought a new EGR valve from Autozone (Wells $99.99) yesterday, put it on today. Didn't help at all, but now there's no SES light. I also replaced the cracked boot on that vacuum hose.

Now I'm going to focus on the fuel system. I put some fuel injector cleaner in, gonna see if that helps any. Guess I'll replace the fuel filter even though its fairly new.

I'm trying to use OBD 2 to monitor my fuel pressure, but I can't figure out how to log it! Its there when I start OBD 2 but disappears when I start logging. Anybody know why??

If something were wrong with my injectors how would I know, I mean what would a see happening? low fuel pressure, hesitation, misfires? Is replacing them the only way to fix it if a fuel system cleaner didn't unclog them?
Please keep the advice coming!!

[Dojo2000]

fuel injector cleaner still running through system. Also changed fuel filter tonight. Still stumbles :mad: [img]graemlins/crybaby.gif[/img]

Another thing I noticed last week is I can hear my fuel pump. I mean it is loud. Its almost as loud as my mom's boyfriend's aftermarket inline fuel pump on his 396 GTO. This is the first time in owning the car I've heard it. Could this be a sign of failure? I searched the board for pump failure to try to find out some of the signs, but no luck. You can't hear it in the car because of the exhaust but when you stand outside of the car you can hear it whine/buzz.

[ August 03, 2002: Message edited by: Dojo2000 ]</p>

[Dojo2000]

Went out and bought a fuel pressure tester kit. When I activate the pump without turning on the car it reads 42 PSI. My Haynes manual says that when I start the car the pressure should drop at least 3 - 10 PSI but I doesn't at all. It says if there's no pressure drop then I should apply vacuum to the vacuum pressure regulator, but I don't know where that is and I don't have a vacuum tester. Guess I'll blow some more money and get one :( Can anyone tell me where the vacuum pressure regulator is?
__________________________________________________
$35 - for dealership to tell me I need a new EGR valve, which I already knew :rolleyes:
$64 - three new coils
$35 - vacuum pressure tester
$ 3 - new spark plug
$10 - new fuel filter
$ 3 - fuel system cleaner
$25 - vacuum pump
_____
$180 down the drain :mad:

The look on my face when I push this POS of a cliff... priceless [img]graemlins/evilgrin.gif[/img]

[Dojo2000]

Checked into the clogged cat/exhaust idea. Took it to the Midas that installed my Ravin. Mechanic there said there was no restriction in the exhaust system. He did point out a ticking noise in my engine bay though. I never noticed the noise while working in the engine bay, but like I said the condition gets worse as I drive around for long periods of time (I had drove around a while before going to Midas). It sounded like a spark tick, like it was arcing or sparking. It wasn't a constant sound, it stopped and started. I've checked all the wires so I'm not sure what it could be. He's got a Bonneville with a 3800 in it, he thinks since I've replaced all the coils it could be the ignition module, among other things

I'm sick of throwing money at this thing, especially since I leave for college in about 2 weeks. Does anyone even read this topic anymore? :(

[ August 08, 2002: Message edited by: Dojo2000 ]</p>