Code 332 will not go away.....

[zagfan]

Hello to all. I am new to the forum, although I have used numerous posts in the past to complete repairs. There are alot of really knowledgable people in here.

Anyway, the exploder has been idling rough, has had poor excelleration and has horrible gas mileage. Borrowed a scanner and the only code was the 332 EGR valve not opening code. The EGR valve, sensor and vacuum solenoid have all recently been replaced. Also have recently replaced plugs and wires, cleaned the MAF, checked for general vacuum leaks and did all other routine maintainance (Fuel filter, PCV, etc). I am at my wits end. Do I have a bad connection between the PCM and the vacuum solenoid, and if so, how can I test that? I would love any suggestions.
Thanks in advance to all.

 

[uh60james]

Sorry I can't provide you with much more help than this. If you need anything else from the manual let me know.
From the manual:

DL - Testing Notes

NOTE: You should enter this Pinpoint Test only when you have been directed here from Quick Test.

REMEMBER

To prevent the replacement of good components, be aware that the following non-EEC areas may be at fault.

- Damaged EGR valve

- Restricted exhaust system

- Damaged vacuum reservoir or canister

This Pinpoint Test is intended to diagnose only the following:

- Harness circuits: VREF, PFE, DPFE, SIG RTN, EVR, VPWR

- PFE sensor

- DPFE sensor

- EVR solenoid

- EGR valve assembly

- Processor assembly

- Vacuum line/tubes (EVR, PFE/DPFE)

DESCRIPTION

PFE/DPFE System



The Pressure Feedback EGR (PFE) system consists of a pressure sensor (PFE sensor), EGR Vacuum Regulator (EVR) solenoid, and a vacuum actuated EGR valve. The Differential Pressure Feedback EGR (DPFE) system uses a differential pressure sensor (DPFE sensor) which has two pressure inlets rather than one as in the PFE system.

In both type of systems, the EVR solenoid regulates a vacuum signal to the EGR valve in response to a duty cycle signal from the Powertrain Control Module (PCM) . The EVR solenoid will vent some of the source vacuum and transmit the remaining vacuum to the EGR valve in response to the level of the duty cycle. The higher the duty cycle, the more vacuum is transmitted to the EGR valve. Due to the design of the EVR solenoid, the available vacuum at the EGR valve never reaches the source vacuum level.

EGR flow rate is determined by monitoring the pressure across a fixed metering orifice as exhaust gasses pass through it. The DPFE system monitors this flow across the orifice directly by supplying the DPFE sensor with a pressure signal before the orifice (upstream pressure) and a pressure signal after the orifice (downstream pressure). The DPFE sensor then evaluates these two pressure inputs and determines the pressure difference across the orifice. This pressure difference translates to a specific EGR flow which the DPFE sensor signals the PCM by means of an analog voltage signal. This signal to the PCM increases linearly as the differential pressure increases. The PFE system, unlike the DPFE system, has only one pressure signal input (downstream) and must rely on the PCM to indirectly infer the upstream exhaust pressure in order to determine the EGR flow rate. The PFE sensor transmits an analog voltage signal which decreases linearly as EGR flow increases.

With the feedback signal that either the PFE or DPFE sensors provide, the PCM can then optimize the EGR flow rate by varying the EVR duty cycle.

 

[MrShorty]

I would have to copy too much from the manual to put the entire diagnostic tree here. The diagnostic tree is different depending on whether or not it's a KOER 332 or a CM 332 (see my notes on pulling EEC-IV codes thread in the EEC-IV forum if you don't know what KOER or CM mean). Basically, a 332 means that the computer sent a signal to the EVR solenoid to open, and the computer couldn't see any change in the DPFE sensor signal as a result. Many possible causes including an electrical problem between the PCM and the EVR solenoid or a vacuum problem between the vacuum port and the EGR valve.

There are several ways to check for an electrical fault between the EVR solenoid and the PCM. Do you have a wiring diagram? If not, the wiring diagram from Chilton's should be adequate as the EVR circuit is pretty straightforward. You could then use an ohmmeter to check for continuity of the circuit and check for shorts to power and ground. You could use the output state test (again see my notes on pulling EEC-IV codes if you are unfamiliar with this test mode) to see if the computer can send a signal to the EVR solenoid. At the same time, you could use a vacuum pump to see if the EVR solenoid is responding. A vacuum gauge between the EVR solenoid and the EGR valve would indicate if the EVR solenoid is opening during engine operation.

 

[dizzybirdtrane]

zagfan, what ever happened with this eh? I know it's been over a year....haha.

MrShorty - are you looking at a manual specific to the emission control system? Just wonderin....I haven't done a lot of searching to find out what manuals are available for all of this. (have same code).

 

[MrShorty]

MrShorty - are you looking at a manual specific to the emission control system? Just wonderin....I haven't done a lot of searching to find out what manuals are available for all of this. (have same code).

Yes. I go to my local library where they have Mitchell manuels. You look for the "Engine performance, driveability, and emissions" volume for your year and engine. Other publishers of professional level manuels that I see show up in libraries are Motor and Chiltons though I haven't seen the Chilton's as much (mostly see their DIY manuels that don't have the complete diagnostic information). The complete EEC-IV section is typically 200-300 pages long.

 

[dizzybirdtrane]

wow, sweet resource. didn't know that existence - most places I've seen selling these types of manual just have generic haynes or chilton manuals for the entire car...not system-specific. neat. well, turns out I don't need to look there - embarassing....after half a week of researching, I realized my roommate put the vacuum tubes on the DPFE/EGR Pressure Sensor backwards, and he and I both didn't notice....this was causing the car to throw CM 332 codes. Put them on correctly and the code goes away. Totally made sense when i thought about it - hoses are backwards, sending wrong pressure/voltage reading indicating the valve isn't where it should be. Attention to detail....attention to detail....haha.