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Egr rant...

VitaminC

VitaminC

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May 3, 2011
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Wichita Ks
87 350 tbi 700r4... Original... Mostly

Okay. For some stupid ass reason I decided to replace the egr, can't remember why, knowing this truck probably an idle problem.
So I go to autozone(I know) and buy some duracrap thing. Spend an hour finding the right tools to get to the bolts and on it goes... Fire up the truck, and it will idle, but as soon as you touch, and I mean touch the throttle it lopes violently and sputters.

So I said f-it and blocked the vacuum line to it... Truck runs great...until

Until it's a 105 degrees outside, then it wants and successfully dies at every stop light. It will start right up, and run to the next light.
So I read and read and I know I'll get the fuel pressure lecture. But, it's strange that at 90-95 degrees it will run its ass off and at 105 it won't.
Anyway, I naturally go back to what I messed with...egr.

Break out the box it came in and sure enough, directions and choke washers. So I tear it back out and install the correct washer, reinstall... Same behavior.
Did I get a bad Asian part??? Incorrect one even? Duralast "egr120". Thoughts??? Ball busting??
Btw, I'd put the old one in but I tore the hell out of it getting it out:)
 
Oh and by the way, it runs with the egr vacuum line open and leaking better than with the new valve hooked up. I have not tested it in the heat yet as it's 420 :) in the morning. Do that tomorrow. I also have some wtf pictures for you guys when I have daylight
 
that'd be my guess, most idle issues end up being an IAC or vac issue... usually EGR's are an off idle stumble/problem..
 
Coincidence that the heat picked up? Or that I replaced the egr? I will do some reading on how to test the iac and get after it.

The egr thing is just so strange. Driving me nuts
 
oh, i would say so... a 10 degree ambient temp increase isn't going to make a difference one way or the other.... bet it would have started doing it if it was 80 out...

has it thrown any codes?
 
No, no codes. First thing I'm going to do is force the behavior by letting it idle in the heat. I wanna look in the tbi and make sure it's getting proper fuel. I also can suspect a fuel pump relay I suppose.
 
Oh and no It won't do it when it's 80. If I drive it at night it acts right. Something is heat soaking bad. I read on vapor lock and got some different opinions on whether a tbi unit is capable of it.
 
Think I found the problem. the temp sensor at the front of the engine is unthreaded and hanging from it's connector!! Unbelievable. There is what looks like an incorrect sensor in the hole it's supposed to go in with hard plastic vacuum line running to it. Off to autozone. will update
 
yup, that'll do it... might wanna take a peak at your plugs after this...
 
I'm probably wrong, but isn't the front sensor for the gauge and the back one for the ECU?
Or am I thinking about another engine?

Plus, I gotta wonder where that line is going. It sounds like a temperature controlled vacuum switch. If so, what is it supplying vacuum to or cutting vacuum off of when it gets to temp?
 
well, I'm not sure what he is referring to about a vac line... the one in the intake is the water temp sensor for the ECM.. the gauge sender is in the ds head..
 
Fordum said:
I'm probably wrong, but isn't the front sensor for the gauge and the back one for the ECU?
Or am I thinking about another engine?

Plus, I gotta wonder where that line is going. It sounds like a temperature controlled vacuum switch. If so, what is it supplying vacuum to or cutting vacuum off of when it gets to temp?
Click to expand...

The coolant temp sensor (CTS) on the front of the intake near the water housing is for the ECM and the temp sensor for the gauge is on the drivers side head. There are no thermal vacuum switches used on the TBI trucks so I have no idea why he seems to have one.
 
On the way to the store I got to thinking. That is not a vacuum line. The PO installed a dial temp gauge (which also doesnt work). That hard line runs into the cab. I bet to that gauge. Lettin the truck cool down as it wants to spit coolant out of the hole.

Thank you for the link. I have not read it yet but I will.

I'll be back
 
VitaminC said:
On the way to the store I got to thinking. That is not a vacuum line. The PO installed a dial temp gauge (which also doesnt work). That hard line runs into the cab. I bet to that gauge. Lettin the truck cool down as it wants to spit coolant out of the hole.

Thank you for the link. I have not read it yet but I will.

I'll be back
Click to expand...
OK, that makes sense. I knew they didn't use switched vacuum so I was wondering what the heck the PO had done.

Can we tell from his description which sensor it is? If its the ECU, then it has a good chance of fixing a lot of his problems.
 
Well that didn't fix it... It's getting fuel... You can smell it under the hood when it dies, maybe just not enough. Still feels electrical to me.

a6898d4c-87e9-0ec3.jpg


Lol this valve cover breather on the tube runs to this...

a6898d4c-8839-5aa8.jpg


Not sure what that's called

It was the sending unit to that gauge in the cts hole...

I'm stumped for now
 
Those pics were off topic, I know that probably has nothing to do with the issue at hand... Just another wtf rig
 
take a pic of the top of your motor, specifacally the left front of the intake where the cts goes..


thats the EVRV valve for the smog pump, not gonna be the issue..

pull a plug and see if it's been running rich... an indicator of a bad CTS
 
How reliable is the dying......I typed that and it sounds weird.......
What I mean is, can you get it to die when you want it to.

We need to try to figure out what is failing. Gas or spark. If its gas, it could be starving or flooding.
If its spark, it pretty much just quits sparking.
Of course, if the EGR was opening when it shouldn't, that would cause a stall also.

I am thinking that a quick and dirty test of the ignition would be to pull a plug wire and either let it spark to the plug so you can hear it, or insert a screwdriver and let it spark to the block.
Then see if the spark quits before the engine does.

Personally, if you are smelling gas, I suspect you are flooding out at low speed. But, of course, loss of spark would result in unburned gas.

As far as the heat is concerned, I suppose it is theoretically possible for vapor lock, but I never heard of it in a TBI.

Since the gas is constantly circulating, it should not have time to boil. If your regulator was stuck closed, it might.
Or if your fuel line ran close to an exhaust manifold..........

Oops, also if your fuel pump was on the way out......
The fuel pressure regulator stops the return of fuel until it goes over a certain pressure.
If the pump was unable to exceed that pressure, you would have a situation like a carb setup where the fuel would be just staying in the line until used.

The truck would still run, although I would expect it to have problems with full throttle because it might overdraw the pump.
 
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