2.0 FI problems again

[JRust]

I've replaced head temp sender, Trigger point & Pvc valve. My cold start valve also is bad. Just unhooked it for now. My little leech ran great for about 10 days after I got it back from the shop. Now its back to doing the exact same thing. Running really rich & backfiring with a nice black cloud out the muffler. I don't want to switch to carbs but this is beyond me & no wrench around here seems capable of fixing it. Or at least fixing in a reasonable amount of time. What do I have left to replace to make this work right. Aux air cooler? All my injectors are new in Oct & hasn't seen much use since then. I would love to get it fixed but am sik of throwing the $ down the drain. Carbs may be my easiest option even though I hate to do it! Please help

[Dave at Pelican Parts]

Have you been through Kjell's D-jet Guide http://www.914fan.net/djet.html and Brad Anders' Everything D-jet http://members.rennlist.com/pbanders ? Read them many times, understood what they are saying? Gone through everything in order (mechanical stuff, valve adjust, etc.--then ignition--then fuel pressure--then FI parts checking)?

I know it can be frustrating at times...

--DD

[mike95125]

Not an expert: But I would do an air leak test. My car was doing the same but with the cloud of smoke being white. I took a can of carb/choke cleaner and used the little straw nozzle to spray near where ever something was attached. I found that the majority of my problem was in air leaks at the #3 & #4 fuel injectors where they seal (with new o rings I might add) to the intake pipes. I got a significant amount of boost in RPM when I sprayed there. I sealed the o rings to the plenum with some good silicon sealer and then tried it the next day. The back fire was gone and I was able to idle much better. Also I am suspecting my dizzy to be bad, this can contribute. Check timing, leaks, MPS as per Brad Anders web page. My other problems are perhaps not the same cause, but I hope this helps.
$.02

[pbanders]

Before diagnosing any FI problems, the following (in order) must be checked first:

1. Engine mechanical condition: valves adjusted correctly, compression good in all cylinders, engine vacuum test AOK (checks for ring and valve problems). All cooling sheet metal in place, thermostat functioning and cooling flaps in place and operating properly.

2. Ignition system condition: all components in good condition and the right parts for your application, plugs gapped right, timing and dwell set properly, vacuum adv/ret cells hold vacuum and work right, points plate moves freely, plate strap in good condition, no shaft wobble, etc., etc.....

3. Fuel system condition: Fuel pressure set EXACTLY to 29 psig, fuel supply sufficient (see Kjell's article), fuel filter not clogged, fuel sock in tank clear and not clogged. All of this MUST be checked before proceeding to diagnosing the FI system.

4. Electrical system condition: System voltage when running must be a minimum of 12V. Alternator, regulator, and battery all in good shape. Battery ground and tranny ground in place and with clean chassis connection.

If you have assured all of the above is ok, then you go to diagnosing the FI system. Here are the steps, in order, that I'd take:

1. Check ALL (not some, ALL!!) FI system parts to make sure they are correct for your application. Use my web page to assist:

http://members.rennlist.com/pbanders/djetparts.htm

2. Check the injector spray patterns to identify any clogged or leaking injectors. See Kjell's article for the procedure. Test the CSV to make sure that it isn't leaking, that it sprays properly, and that the thermoswitch (or thermo-time switch) operates at the proper temperature.

3. Make 100% certain that all vacuum lines are properly connected and that there are NO vacuum leaks. This means assuring that all of the vacuum hoses are in perfect condition, if there is any doubt, replace the lines. Use Dave Darling's diagram here on the PP web site to check. Also, check every single possible place in the intake system for vacuum leaks. This includes: throttle valve shaft, throttle valve gasket to the plenum, plenum seam (can be cracked), CSV gasket, dizzy vac adv/ret cells, intake runner boots, injector seals, etc., etc., ad nauseam. Also make certain that the crankcase breather valve (on top of the oil filler) is working properly. The method of choice these days for checking for vacuum leaks is visual inspection and the use of a small propane probe - anybody got a source for these?

4. Check the TS1 and TS2 sensors for the correct hot and cold resistances. Use my web page above to get the correct values. Make sure the TS2 connection to the wiring harness is not in contact with the plug wire and that there isn't any bare metal touching ground, and that the sensor connector is FULLY seated in the wiring harness spade connector.

5. Test your throttle position sensor to make sure that the idle contact is being engaged when the throttle is closed and that you get all 10 on/off transitions on each of the accelerator tracks as you open the throttle from closed to fully open. See the TPS article in the Pelican Parts tech article site for instructions.

6. Pull your ECU and from the wiring harness plug, test each of the connections for the proper voltage or resistance. See my web page above for values. This tests both the harness and the components. Make sure you crank the engine and test the trigger contact points for proper operation. Examine and clean the FI grounds from the wiring harness that connect at the back of the engine. When connecting the harness plug into the ECU, make sure it is fully seated and that the plastic cover that goes in the end of the ECU is present and properly seated, and that the ECU harness clamp is present and firmly attached to the harness.

7. Test your auxiliary air regulator for proper operation. It should be fully open when cold and close on its own when +12V is applied to the wire after about 5 to 10 minutes. If it doesn't close, soak it in solvent to free up the mechanical component. If that doesn't work, use the Dave Darling method of taking it apart and fixing it. Make sure that the resistive heating element is still working, check my web page for the proper resistance value.

8. Check your overrun shutoff valve (vacuum limiter) to make sure it's functional and not leaking.

9. Check the manifold pressure sensor for proper primary and secondary resistances. Check that the sensor holds a vacuum, if it doesn't, it must be replaced. See step 11 for functional testing. Check my MPS web page (see URL below to navigate to) for extremely detailed stuff on the MPS, if you're so inclined.

10. If you get to this point and still have a problem, it may be with the ECU. The only way to test the ECU is to use a tester. Rent the VW1218 tester from Pelican Parts. It tests every ECU block for functionality. It also does a static and dynamic test of the TS1 and TS2 sensors, checks the trigger contact points, and does a functional test of the MPS.

If you've gone through this list (I'm sure I've forgotten something, please contribute if you see something missing) and everything tests out AOK, you can send me email or post to the list here and we'll try to help.

Common reasons why an FI system is screwed up:

1. High or low fuel pressure.
2. Low fuel supply due to fuel filter clogs or supply line clogs.
3. Vacuum leak from hoses or injector seals.
4. Wrong vacuum hose configuration.
5. Inappropriate FI component (wrong p/n for the application)
6. Dead TS2 sensor.
7. Wrong TS2 sensor.
8. Dead MPS - vacuum leak due to cracked full-load diaphragm.
9. Leaky or inoperative CSV.
10. Leaky or clogged injectors.
11. Dead (stuck open or stuck closed) or missing aux air regulator.

[JRust]

Wow thanks for the input guy's. Brad your explain thing well. Thanks for going in to such depth. I appreciate that alot. Any chance you want to make a trip to Oregon. I do have great Pizza & would gladly feed you well. So free pizza to you if you want to come fix it for me. In all seriousness I realize I need to just go thru this & learn it myself so I know how to fix it. Its a little intimidating I guess. It's also about the time. When I'm not at my store I have a hard time working on my car without neglecting my family. Well I'll figure it out eventually. I just get very frustrated with my little leech sometimes (more like every day). Thanks for the encouragment guy's