Thread: 496 fouling plugs

Tweet

change the flow ratings of the injectors-------------------

Bob,
I just re-read your thread. You mentioned up in post #14 that your AFR is reading 20.94 and 17.92 at different throttle positions. Ideal is 14.7 air to fuel, so your numbers are getting into the critical lean area, if they are correct. With those readings you're still smelling raw fuel and fouling plugs like crazy. That says to me that your ECU is cranking your injectors wide open trying to correct the critical lean situation, but even with that the ECU is still seeing super lean feedback. All of that could point to a faulty O2 sensor. Now it may be that you've simply plugged the sensor with carbon, masking it from the exhaust. You might try pulling the sensor and cleaning it, but I think that I would be investing in a new O2 sensor which may need to come from Edelbrock. With all the trouble you've had they might just send you one under warranty. Sorry I missed those AFR readings before. I'm hoping they're the telling tale you're looking for, along with the strong gas aroma clue you shared.

sense Mark is on vacation and the other techs I have talked to didn't help i well pull the O2 and take a look

Bob-is there a procedure to zero/calibrate the o2 sensor reading before initizing the programming/startup??????? and do you have the proper O2 sensor??? wired correctly??? how many wires are on it???????If you need a wide band probably can get it at a VW dealership------


Does this car have cats? and if so have you ever run race gas???(lead)


And does your msd have start retard?????? Can you lock out advance curve so you could just set timing to around 30-36 degrees??? If you have start retard you can probably set timing advanced to run specs for 3000-5000 and use the retard module to idle back, shut down, start up------------


did you have the vacume disconnected when you set the timing???? and what vacume does the engine pull????saw edelbrock said that needed 10 inches

I am probably repeating what has been said before, but sometimes it is worth going back to the start and trying again. A couple of points to note first,
1. efi will start in open loop until engine temperature is at an optimum level and the cats / exhaust and O2 sensor at working temperature before going into closed loop. This requires a base map that for your system is selected in the first part of the setup sequence. Will probably run a little on the rich side to be a safe tune, but if running rich in closed loop, it may actually run better in open loop, this would point to an O2 sensor issue.

2. The O2 sensor is critical, it needs to be clean and all connections made properly. You can try cleaning it, but sometimes a new one is the only way to know it is ok. I believe it may be earthed through the exhaust system, sometime a wire can be added to earth through to chassis to determine if there is an earthing problem.

3. The installation guide stipulates spark plugs and leads. The ignition system needs to be working properly, ie set right with the right advance curves. Plenty of threads on how to set the timing, can the marks on the balancer be trusted? If you don't want to set the timing properly then set the timing to where it idles best when it is in open loop, which maybe the best starting point ie not perfect. As the efi is not doing anything with timing this needs to be right as the efi unit is adjusting fuel to get a target afr for a "normal" combustion profile. This could even be your original problem when running the carb.

4. Thermostat temperature. Manual says over 160, modern cars can be up to 215, I would guess around 180 to make sure.

Once the above is sorted out I would go through the installation checklist as if I had not done it before, assume nothing and check everything.

When it comes to the efi setup with the tablet, I would do it from scratch, ensuring that engine size, cam specs, etc are entered correctly. Again I would go through this as if I had never done it before, step by step. I might even leave the air cleaner off to make sure there is no fouling of linkages etc during the setup.

Efi is no different to a carb setup, just more stuff that can go wrong, or more precisely easier for a few simple things to not be perfect and together the motors runs like crap.

The engine with air, fuel and spark will go bang, just keep it simple and eliminate one thing at a time, also if it is frustrating you, walk away for a bit.

Good luck, you've come to far to just give up, so may as well enjoy the last little stretch of getting this sorted out.

Bob,
JL350's advice is good on every point, very thorough and informative with a logical, systematic approach. One thing that he mentions in point 3,

can the marks on the balancer be trusted?

On my SBF balancer there are three or four sets of index marks, to match up with different locations of the pointer on different applications. My engine guy made a point of telling me that he'd double checked the alignment and marked the correct zero point with a dot of red paint. It would take one thing off of your list of possible gremlins to verify your zero line before you go much farther. Lots of ways to do that, but one of the best I've found is back in this old thread - Lord knows you have an old spark plug laying around that you can hot glue to some tubing
Finding TDC
If you don't like that one, Tech posted a link to a Crankshaft Coalition article that describes another method and the stuff there is top notch, too.

Another item --------the O2 sensor should NOT be mounted in the bottom of the exhaust tube--------but upwards from the bottom curve to as high as you can get it so it doesn't get contaminated with liquid stuff-----------


I can't get rid of the gut feeling that there is an exhaust leak prior to the O2----------------

O2 sensor is cover with black carbin on it. as far as TDC checked that with a camera do the plug hole, temp is good, talked to tech again and waiting for the Big Dog to come back from vacation. tell then am putting an MSD system in her. The O2 is 10 degree angle from center of pipe all where they want it. I redid everything on the install and reprogramed the ECU which I found out latter that you are not to do this to much but they said twice is ok.

Many times you run into a problem with the ecm seeing a lean fuel mixture because of a miss fire one or more cyl's are not running so the products of the combustion being air and fuel the air is 21%. o2 that is normaly converted to co2 (ya know that stuff the idiots hate) but is not converted so the 02 sensor see's that o2 and not capable to measure fuel tells the ecm ha dude this thing is way too lean get off your ass and richen up the a/f mixture. So look for a miss fire ignition, vacuum leak, plugged cat, egr. valve, mechanical prob. valve, cam, piston, or? time to go back to the basics....ted

What pinged my radar was the comment that the 02 sensor could have bad ground. That is something I would definitely overlook. That is to say, easily assumed ok.

ground is good There is not cats just headers and trush mufflers. I have changed plug wires and plugs, coil, cap and rotor

Bob, feel for you, but on the brighter side you will know the system inside out before long. Also it is difficult to gauge what you do and don't know so please don't take offence if I say some really obvious stuff, just trying to help.

Efi is bullet proof when everything works, it will not work if it cannot measure key parameters accurately in a certain period of time.

Any parameters it is not measuring either directly or indirectly, it will use tables of "expected" values to calculate the fuel corrections. If these values are NOT as expected it will generally adjust what it is controlling and wait for a response from what it is measuring, if it does not get the expected outcome it will er on the safe side and make a rich situation. Think picking up an eggshell, but you cannot feel it and you cannot drop it, you squeeze harder and probably break it.

From memory your efi uses hot side water temperature, O2 sensor, throttle position sensor. Some of the assumptions it is making it that there are no air leaks around the intake, good air flow through the air intake, ignition is firing at the right time for the right cylinder, there is no air or exhaust leak between the cylinder and the O2 probe. All of these parameter and some others then allow calculation of the correct change of fuel addition to target the desired air fuel ratio which is the self learning process.

I don't thing the parameters somewhere in the system are close enough to get the self learning working properly, the efi is then either going rich because it thinks it is lean, or it is going open loop because it can't figure out what is going on, and this also results in a rich condition.

If it was my money, I would be looking at something other than the efi causing the rich condition given that the problem happened with the carbs as well.

I would check for vacuum leaks around the intake and I would absolutely make sure the ignition is right. Can the cam cause the problem? Is the sump pressuring causing oil blow by? Do you have a temp gun to shoot temps of the exhaust manifold to see if there is a problem cylinder with either high or low temp?

The O2 sensor you mentioned is covered in soot. Is it a self heating sensor or does it require the exhaust temp to heat it. The sensor needs to get up about 600 F to work properly and burn off any buildup. If there is anything on the sensor it will read a lean condition. Contaminants such as silicon, carbon, grease, oil, even finger prints can cause issues. You maybe able to clean the probe, but you may never know if is clean enough, or if it has been damaged.

On another forum I go onto, a Ferrari was having misfire issues, when they added an extra earth wire from the O2 sensor to the chassis, the misfire went away... They tried this because they couldn't measure any voltage or resistance issues, just something to eliminate.

Good luck

Bob---------If you want to solve this and are willing to work with me via PM, (I know you are with RS) and for a short period of time, exclusively follow the procedures I suggest, I am willing to help you further-------You are new here so probably don't know anything about my background , so you can google Keeling & Clayton California Charger and go from there-there are people on here fully aware of where and what I've done, and it creates more problems with some than it helps with others---
You can ask the people at Edelbrock about us and you can start at Vic himself or for this ask Chris Johnson( he used to be at Diablo? before Edelbrock)

Am going to give Edelblock a chance. But winter is coming so time is about up for driving. I got a new MSD Pro Bullet Distributor and the MSD Digital 6 box ill see what happens and let everyone know.

Originally Posted by bobsundance

getting to that point but have to give Edelblock a chance but winter is coming MSD ignition now from dist on plus box we well see. Well let everyone know

Bob,
I think what you're saying is that you're going to work with Edelbrock (now that you have the right point of contact and he's back in the saddle this week); and that your ignition is now a new MSD distributor and new MSD box, right? No disrespect, but it gets really confusing with no capitals/punctuation to break the words into the sentences you intend. It makes reading a post a guessing game, and your meaning can easily be misunderstood.