I got a check engine light that came on briefly the other day when I was going up a large bridge and had to floor it to keep up speed. Then today, it had trouble when I pressed on the gas, and then stalled. Couldn't get it started for about 10 minutes or so, but worked pretty good after that.

Checked the codes and got this

33 ALL - (O, M) EGR did not open/ respond during test or if memory code, did not open intermittently - EVP EVR PFE

and

53 Throttle Position sensor too high - TPS


I replaced the EGR valve about 2 1/2 months ago. I keep having idle problems and surging when stopped(sometimes it surges so much it stalls). It helps calm it down when I put it it Neutral though. I've also checked the spark plugs, wires, cleaned the throttle body(althoug it was totally free of deposits really), and checked the air bypass valve(don't know if it's working right, but it moves and is not gummed up.

I am going to replace the TPS today anyway b/c this is one thing that someone thought may be wrong with the idle problem.

So what is 33? It was in memory, so it didn't open intermittenly(whatever that means). Does that have to do with the vacuum regulator maybe? Any help would be appreciated.


Brian
1988 Eddie Bauer 351

 

code 33- EGR valve closed, erratic or has insufficiant flow.

I'm fighting this problem as well....

New EGR and position sensor = same code, no check engine light.

See my post titled a few questions-help please for my experiance with this.

 

The throttle position code is telling you that the air bypass valve is faulty and needs to be changed......also change the potentiometer when doing this....

THe EGR valve may not be opening due to either bad EGR selenoids (3 mounted next to the coil on the driver side valve cover) or a vacuum line is broken/disconnected....

carefully scrutinize all of these....

DO change the EGR selenoids.....everytime you change the EGR valve.

 

Potentiometer?

selenoids?

Would these be in my Chilton manual? Hopefully....



Brian

 

THe potentiometer is a small black pill type electrical sensor that mounts on the bottom of the throttle body (you will have to remove the TB assy to get this off.....

it will have 3 to 4 wires and an electrical harness connecting to it...This sensor gives electrical voltage readings to the ECU
telling it specific info about throttle position....and based on the contact point the throttle is touching, this is the specific voltage the ECU will recieve and relay to the fuel/emissions system.

THe EGR selenoids are the units that help relay vacuum and electrical info to the EGR valve and engine (these act as an interface to both engine and EGR valve)

2 are small black cubic boxes that are usually mounted
the 3rd one is cylindrical and has a grey top.....
they should all be mounted next to the coil...towards the rear of the driver side valve cover...

they should be covered in your chiltons manual.

with these burned out, your EGR valve can remain non functional.....forcing your ECU unit to keep spitting codes out.

 

I think the potentiometer you're speaking of is the TPS(Throttle Position Sensor) round, black, and 2 screws, and 4? wires going to harness. I've got that part and was going to replace it. If that doesn't work I was thinking about replacing the Idle Air Bypass Valve.

I'll check the Chilton as well.
Thanks!

Brian
1988 5.8L 351 EFI

 

I disagree with Capone - the TPS code only indicates the TPS; not the IAC. But it may be causing a fault because a) you held it floored, b) its wires are shorting/open, c) it's slightly out of adjustment, or d) it's bad. Haynes tells how to diagnose it.

There's only 1 solenoid vacuum valve that controls the EGR. (The other 2 control the smog pump system - "thermactor air".) It applies & vents vacuum to the EGR diaphragm to control the flow, while the EVP reports the position to the computer. The EGR code almost never means the valve is bad; it usually means there's a vacuum leak, the solenoid isn't working, or the EVP has a problem. Haynes tells how to diagnose each component, so don't just replace them without identifying the problem first. Throwing money at it almost never works.

 

It isn't that I threw money at the situation.....the truck had 130k miles on it and it needed the manufacturer suggested replacement of the sensors etc anyway.

We did kind of say some of the same things in a different way though.......

I did not specify that the EGR has to be bad, I merely stated that EGR codes can be a faulty selenoid.....

Since I was at it and like my cars to run trouble free, I changed em all out.....(if you get parts at wholesale, why not?)

Regarding the TPS (or as the deaer calls them Potentiometers)
They recommended changing it along with the Air Bypass valve...
due to the mileage.

My Bronco also had alot of symptoms that warranted these parts being replaced.....

If the symptoms are very limited, do follow the correct diagnosis procedure depicted in Chilton's manual.....the emissions and sensor systems are covered in that bad boy.

 

I'm changing out the TPS this weekend and maybe the IAC. Along with all gaskets.

I have a new EGR and EVP, so it must be a (vacuum leak or the solenoid isn't working). I have a vacuum tester. What should it be on idle at the little tube that goes into the EGR? I can feel a suction, but very little.

Brian

 

[updated:LAST EDITED ON 14-Dec-02 AT 00:12 AM (EST)]You can't test the vacuum at idle - the system only works when the engine is at a high enough temp, under enough load, & at a high enough RPM that the additional gas won't affect it. If you e-mail me, I'll attach the MityVac manual that I scanned & OCR'ed. It explains the system and how to test it. It's a big file, though...