Got an engine miss devoloping...

[HotRodPC]

[yt]VUaYozSNDcc[/yt]

Have you replaced that PCV valve? If it's defective, it can sure cause some rough idle issues. And I have a feeling that rattling is the ball going back and forth which would mean, it's not acting as a one way valve as it should. By chance and you seeing and blowby out of the crankcase anywhere? As in excessive, not a small normal amount for a worn engine, but heavy blowby? I would replace that PCV for sure though.

 

[HotRodPC]

WTF??? Are you setting timing with a broom???

 

[89Suburban]

Have you replaced that PCV valve? If it's defective, it can sure cause some rough idle issues. And I have a feeling that rattling is the ball going back and forth which would mean, it's not acting as a one way valve as it should. By chance and you seeing and blowby out of the crankcase anywhere? As in excessive, not a small normal amount for a worn engine, but heavy blowby? I would replace that PCV for sure though.

I'll have to do that I guess, it's brand phukin new though....

WTF??? Are you setting timing with a broom???

I use that to tap the ear on the dizzy cap one way or the other when adjusting the timing. Keeps me from getting shocked, killing my back and knees, and getting my nut sack caught in the engine fan or hood latch.

 

[RetroC10Sport]

and getting my nut sack caught in the engine fan or hood latch.

I've never had that problem.

 

[bucket]

I once slipped and caught my chest on the hood latch. Ouch.

 

[89Suburban]

Ok Jim, I know you are away and having your own issues but if you get bored got anything to add comparing these 2 EGR styles? They are both off similar year TBI motors. The larger one seems to have a shielded area around the incoming port. All other ports look the same though, the 2 small holes in each and the port feeding the intake manifold look the same. I tested these with my vacuum gauge and they both operate similar and hold a vacuum.

 

[89Suburban]

Ok, this is VERY enlightening.


"EGR flow is also undesirable at other times, for instance at idle. At very low speed, combustion temperature is naturally lower. Adding exhaust gas at low speed can cause rough idle. The positive back-pressure EGR valve helped solve this problem."


http://www.agcoauto.com/content/plugins/p2_news/printarticle.php?p2_articleid=207

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[89Suburban]

Too Much of a Good Thing
I’m working on a 1992 GMC K1500 pickup that has a 5.7L engine and about 150,000 miles on the odometer. The engine stumbles on light acceleration when the EGR valve opens. If the vacuum hose is disconnected from the valve, the engine runs great. The readout on the scan tool indicates the valve is operating, but it seems to be opening too soon or has too much flow. The EGR solenoid is opening and closing properly and the EGR valve is not stuck open or closed. I’ve also checked the TPS and MAP sensors and both are good. All tuneup parts also are good.
John French
Lancaster, CA

A positive-backpressure EGR valve can be identified by the letter “P” stamped next to the part number and date code. Positive-backpressure EGR valves are used in simple vacuum-controlled systems, as well as more complex pulse-width-modulated applications. A positive-backpressure EGR valve’s hollow pintle shaft is much thicker than that of the single-diaphragm type. The hollow design allows exhaust gases to flow into the shaft and push up on it. When positive backpressure in the exhaust system is sufficient, the shaft raises and seals the built-in control valve. Once the control valve is closed, it allows applied vacuum to pull up on the diaphragm. Without backpressure to lift the hollow shaft and close the control valve opening, vacuum is bled off to the atmosphere. This design modulates the applied vacuum to modulate EGR flow. As engine load and backpressure increase, the EGR control valve traps vacuum and the valve opens.

To test a positive-backpressure EGR valve, bring the engine to 2000 rpm to create exhaust backpressure, then apply vacuum to the valve. The valve should open and cause a drop of 100 rpm or more. Exhaust leaks or a modified exhaust system can cause problems with this type of EGR system.





http://www.motor.com/article.asp?article_ID=1257

 

[89Suburban]

 

[HotRodPC]

Not sure if you're aware but this is a good time to have a Vac pump for diagnosis.

So if your motor is stumbling and idling like ****. Put a Vac line on the EGR to your Vac Pump and pump it. If no change, then that means your EGR valve is stuck open and that's probably your problem. If you pump it and it gets much worse or kills the motor, then your EGR is PROBABLY OK, but not 100% so. The EGR could be hung up just a little bit open.

Also to test an EGR on good running motor. Hook Vac line and pump the pump. The motor should stumble badly or maybe even die. If it stays running, release the Vacuum and it should smooth right back out. If not change to a good running motor, then the Vac daiphram or pintle to your EGR is bad and the EGR is not functioning and you'd fail an emissions test IF THEY TEST it. Some states just do visual. If it's there, then good to go whether it works or not.

 

[89Suburban]

Not sure if you're aware but this is a good time to have a Vac pump for diagnosis.

So if your motor is stumbling and idling like ****. Put a Vac line on the EGR to your Vac Pump and pump it. If no change, then that means your EGR valve is stuck open and that's probably your problem. If you pump it and it gets much worse or kills the motor, then your EGR is PROBABLY OK, but not 100% so. The EGR could be hung up just a little bit open.

Also to test an EGR on good running motor. Hook Vac line and pump the pump. The motor should stumble badly or maybe even die. If it stays running, release the Vacuum and it should smooth right back out.

Well I am trying to get the right EGR on it first, this helps me identifying it, I am going out to the garage right now to check for that code letter on the ones I pulled, wish me luck.

 

[89Suburban]

Nope, all 4 are marked "N".

 

[HotRodPC]

Nope, all 4 are marked "N".

So you need one with a P? I wonder if I have one on that 305 intake out in the shed. ???

 

[89Suburban]

Yup, need the "P" at the end and I think the part number has to match so it works with the computer setup? Still doing my homework on this. If i can get one off a 350 TBI motor with a P on it that bitch is getting installed. Come to think of it, I never looked at the code on the one that is on the truck now, doh, I better do that huh?