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TBI 350 - WOT Hesitation Under Load

Are you running true dual exhaust and headers? A heated O2 sensor may be a big help, you may be also having issues with the computer if the old O2 sensor wasn't getting hot enough. As far as the egr goes, is there a good reason not to have it functioning properly?
 
Shorty headers with fake dual exhaust. Single 3" to cat, then muffler, then split.

As far as EGR, the main reason not to have a functioning one is that i've fought it for months, and just have other priorities right now.

When hooked up (with NEW solenoid), I get this awful 1/4 throttle surging around town. Whole truck bucks. Plugged, i don't have this issue.
 
dhcomp said:
Sh
As far as EGR, the main reason not to have a functioning one is that i've fought it for months, and just have other priorities right now.

When hooked up (with NEW solenoid), I get this awful 1/4 throttle surging around town. Whole truck bucks. Plugged, i don't have this issue.
Click to expand...


Oh thank God, another person with the exact same problems I've been going through.....:waytogo:

I thought I was going to lose my mind trying to figure out what the fock was going on until I took off and plugged the vacuum line off the new solenoid and it cured the same 1/4 throttle surge.
 
snuffy74 said:
Oh thank God, another person with the exact same problems I've been going through.....:waytogo:

I thought I was going to lose my mind trying to figure out what the fock was going on until I took off and plugged the vacuum line off the new solenoid and it cured the same 1/4 throttle surge.
Click to expand...

For almost a year, i had really bad surging RIGHT off idle, at 1-2mph, which is a problem when moving boats around constantly.

FINALLY found the EGR solenoid to be faulty. Then, a few months later, this other surging issue started. So EGR solenoid was tested/replaced again, still surged, so i plugged it.

Sounds like it won't negatively affect anything but my smog test? I'll plug it back in for testing i guess....
 
If you are thinking about changing the O2, there is a trick I don't see used much anymore, but it still works.
You pull the sensor, and hook up a pressure gauge to the hole. You should not see too much pressure.
I don't remember now what was the upper limit, but a couple of pounds was about it I think.
A lot of mechanics had made an adapter to fit the port and hook up a pressure gauge. I suppose you could put a piece of thick cardboard over the hole and feel the pressure with your thumb as long as you did not wait too long for the pipe to heat up.
 
Fordum said:
If you are thinking about changing the O2, there is a trick I don't see used much anymore, but it still works.
You pull the sensor, and hook up a pressure gauge to the hole. You should not see too much pressure.
I don't remember now what was the upper limit, but a couple of pounds was about it I think.
A lot of mechanics had made an adapter to fit the port and hook up a pressure gauge. I suppose you could put a piece of thick cardboard over the hole and feel the pressure with your thumb as long as you did not wait too long for the pipe to heat up.
Click to expand...


I'm guessing to check backpressure, and decide if the cat is clogged?

I like it, good idea :thumb:
 
dhcomp said:
I'm guessing to check backpressure, and decide if the cat is clogged?

I like it, good idea :thumb:
Click to expand...

Uhhh, yeah. I guess I never got to that part did I? The way I wrote it sounds like some weird kind of mod.
I don't know exactly why I don't hear about it as much as I used to. For a long time, every mechanic I knew had a pressure gauge with a couple of adapters just for that.
It was along about the time Cats were just coming in, and there was a lot of distrust of them, a lot of which was justified.
Melted, stopped up, and other type damage was common, and would drive you nuts if you didn't know it had that much restriction.

Of course, since replacing one was very expensive and sometimes had legal ramifications, so it was nice to have a way to test for problems.
 
dhcomp said:
Shorty headers with fake dual exhaust. Single 3" to cat, then muffler, then split.

As far as EGR, the main reason not to have a functioning one is that i've fought it for months, and just have other priorities right now.

When hooked up (with NEW solenoid), I get this awful 1/4 throttle surging around town. Whole truck bucks. Plugged, i don't have this issue.
Click to expand...

The reason it surges with the valve hooked up is because the egr valve itself is bad. The spring inside gets weak, and lets it open to easily.
 
black dawg said:
The reason it surges with the valve hooked up is because the egr valve itself is bad. The spring inside gets weak, and lets it open to easily.
Click to expand...

But, if i plug the EGR solenoid's vac feed, wouldnt' the egr valve still fluctuate if the spring was weak?

I never know whether to attack the solenoid or the valve when i have egr problems....
 
dhcomp said:
But, if i plug the EGR solenoid's vac feed, wouldnt' the egr valve still fluctuate if the spring was weak?

I never know whether to attack the solenoid or the valve when i have egr problems....
Click to expand...
No once the solenoid is off the EGR doesn't move and the engine will compensate for whatever position it's in.
With EGR I tend to think it's the valve that is the problem before the solenoid.
 
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