I have noticed in the past my wideband A/F ratio being lean at WOT. At first, I thought the meter maybe off. I still think it is still possible for the A/F meter to be possibly wrong. Then about a month ago, I took the car for a test spin. At idle and at cruising speeds, the wideband indicates about 14.4 and the fuel pressure gauge indicates 58 to 60 psi. However, a month ago, the A/F ratio goes to 15.2 when at WOT. If it were not for the gauges, I would not know I have any problems whatsoever. The car runs GREAT.

With all this said, I haven't got into a big hurry to get this problem fixed since the car spends 95% of the time setting in my garage. AND yes, it is a garage queen. Recently, I changed the fuel pump filter, this did not help. I have a Racetronics fuel pump, so I thought it may have been a grounding issue. Voila, I thought I found the problem. The ground on this was bonded to the painted chassis with a paint bolt. So, I ran a #10 awg ground back to the battery to eliminate grounding issues. This did not prevail. When I take the car for a test spin, it does the same thing except now it goes to 14.9 A/F ratio and 52 psi fuel.

The only difference I have found is a month ago when the temperature was about 55 to 60`F, I got 15.2 A/F. Today, when it was about 70`F, I got 14.9 A/F. However, neither of these A/F are what I desire. The car was tuned 2 yrs ago with a 13.2 A/F at WOT.

In addition, I tried my best to get Racetronics support to give me a hand. But I could never get them to return a call or an email. Therefore, I came a hair of ordering a new Racetronics fuel pump from Thunderracing. But after talking with Thunderracing, they felt most likely I do not have any problems with the pump but rather with something else that is causing me to possibliy have problems. Other than dropping the fuel tank and pulling the pump to see if the sock is partially clogged, I don't know what to do. I feel if I have to drop the tank, then I shouldn't take any chances and go ahead and change the pump. I certainly don't want to go thru that again. I know there is any easier way to access the fuel pump by cutting an access hole. However, I don't want to deface the car in shape or form.

With my long winded topic, does anyone have any suggestions? By the way, Thunderracing told me to check the fuel pressure regulator. I told them I thought the fuel pressure regulator was part of the Racetronix kit...and they said no it is seperate and in the tank. First of all, I don't think it is the regulator since it works well at idle and cruising speeds. The only way the regulator is not working correctly in my situation would be it is not getting the supply it needs to regulate properly.

Where is the fuel pressure regulator on our cars? (4th gen f-body)

HELP I am Lost on this. Any suggestions would be greatly appreciated.

 

"and they said no it is seperate and in the tank."
Have you checked the voltage at the pump connector?

 

Check this thread out.

You are incredibly lean at WOT. Are you commanding more fuel? If so, check that you're getting good voltage to the pump (13+ V). Fix that, and if you still have the issue, it could be the in-tank FPR. It does have this annoying little feature of reducing the pressure with the flow past it. That's why I gutted mine and went to an external regulator.

 

I have not checked the voltage at the pump connector. I thought this would be very difficult to do at WOT. As food for thought.....the car looses the pressure only at WOT and loaded. You cannot see a drop in pressure when in park and reving up the engine. You literally have to drive this car at WOT to see this drop in pressure.

I am going to try what Fran D referred me to first....https://ls1tech.com/forums/showpost....3&postcount=22. Hopefully, I will find my problem here. However, if this does not prevail, I reckon I will splice into my pump electrical connector and run leads from the cabin of the car out to the connector. I have a Fluke 89 which is capable of recording the voltage.

Appreciate all the help you guys have given me and if anyone else wants to chime in, please do so.

 

Here are a few things to check:

1 Does the pressure fall immediately when you shut off the key?
If it falls immediately, the regulator or an internal line is likely leaking.

2. Are you running the Racetronix wiring harness?
There is no need to run a ground to the battery. This actually causes a greater voltage loss than a good chassis ground. Think of how large of a cable the entire body is equivalent to. Are you running the front battery to chassis ground?

3. How much power is the car making?
This can determine how hard you are pushing the pump.

4. Check the voltage at the pump at idle.... no need to do full throttle yet.
If it is OK, then it should be at full throttle as well. You do need to determine that the entire system voltage is not dropping at full throttle due to an alternator or charging system issue, but that can be checked easily with leads to the battery.

 

Haven't had time to do all the checks you have metioned. However, I found there would be extra insurance if a ran an extra ground from the battery to point where the fuel pump grounded on the chassis. This point originally had a painted bolt fastning the ground to the painted chassis. As you and I both know this is not a good ground. Therefore prior to bolting everything together to the chassis ground and the extra battery ground, I removed the paint from the chassis, added a metal washer, and exchanged the painted bolt for a plain metal bolt. After getting everything put together under the car, I put aluminox over everything to help pervent corrosion.

As for the fuel pressure falling completely off when turning the car off, I don't think it happens, but I will for sure check this. This is a great piece of information you have here. I sure did not know this would give a good indication of whether the regulator was good or not. Thanks.

The car is only making 412 rwhp on a A4. I don't think this would cause the problem we are seeing. However, I have been wrong many time than right.

However for the rest of the problems I have been having the following is what I have found:

It was a real pia to remove the alternator so I could look at the exciter wire plug. When I removed the alternator, I found 2 things. 1.) The alternator sounded like a bad squeeking hinge on a door when you turned it. It was not the pulley rubbing. It is actually inside of the alternator. 2.) The exciter wire is way too small and too short. It appears as if when the engine would torque up, it would pull hard on this wire. Possibly causing this wire to come disconnected.

It's too late for me to make it to a stealership to get the parts I need. I will try tomorrow and if weather permits, will give it a road test.

 

Mine is doing the same thing at WOT right now. Its at the shop now too. Hopefully in a couple days, I can tell you what they found out with mine. Then you can check out yours.

 

Just checked my fuel pressure at the fuel rails with analog gauge you screw onto the fuel rails. The pressure at idle is 65 psi and when I shut the engine off it immediately falls to 50 psi. Is this normal or should the pressure gradually bleed off?

 

Does it continue dropping to zero? How fast does this happen?

 

No, it just holds at 50 psi. I watched it for about a minute and quit watching after that when it didn't go below 50 psi. I'm starting to think possibly I may have a stuck injector. Is this possible to have this condition? I don't run cats or muffler and I have severe black carbon on the exhaust pipe after running only about 5 miles. The carbon on the pipes, the rich smell, and the burning of the eyes tells me (maybe wrong) that I am running rich. But the A/F meter and fuel psi tells me different.

Could it be if a stuck injector tells the car to lean out to read correctly on the O2s and when at WOT, the fuel pump can't keep up due to a bad injector.

Just fuel for thought. Any input would greatly appreciated. I will begin pulling the spark plugs tomorrow to check the conditions for possible imbalance injectors.

 

Just got done checking my plugs and took advantage of the circumstances and did a compression check. The compression on the driver's side and passenger side heads checked good. The driver's side compression read anywhere from 210 psi to 220 psi. The passenger side head read anywhere from 200 psi to 210 psi. Everything within 10%.

However, my check with the spark plugs did not come out as expected. The plugs did show some lean conditions with the #6 cylinder being extremely lean. Check out the pic. From left to right are cylinders 2, 4, 6, and 8.


Does this mean my #6 injector is not firing or maybe clogged?

 

That is not lean....

The white shows the plug is hot enough to burn deposits off the porcelin. See how black the body of the plug is, it would be tan or white if very lean. You need to look into the plug to see the coloration.

Are there speckles on #6 porcelin? This could be detonation. It does appear to be leaner than the rest & note the body has some grey on it as well.

It is very hard to look at a picture & read a plug. I'm just trying to give some pointers. To properly check plugs, you need to use new plugs without deposits on them. Then make full throttle passes, immediately kill the engine without driving it or idling & then check the plugs. Anytime it idles, it is lean, so it alters the readings.

 

I have been looking at several things. 1.) is my stock fuel rail ok for 600 flywheel hp? If not, I am looking at changing this out. 2.) The #6 spark plug could be telling me the injector did work once upon a time. However, after reading thru Ls1tech, I found cars that sit alot like mine without being driven have had injectors to clog up. This maybe the case with the #6 spark plug being so white. I'm don't know how to test this injector to see if that is the case. In addition, if I go with aftermarket injectors (mine are factory injectors), which ones??? My car n/a is 412 rwhp on factory injectors w/100 shot wet nitrous. Won't run the nitrous ever again until this problem is resolved. 3.) Once I get new plugs, plug wires (I broke some of the wires getting them off, I always break the one on #6 and #8), and maybe new fuel rails and injectors, I will be testing the fuel pump one more time before dropping the tank. Once I drop the tank, I won't take any chances....I will replace everything in the tank to get the require fuel delivery my engine needs.


Any suggestions?

 

I know this post is over a month old. However, I hate it when someone posts a problem and never shows anyone what they had found. So here goes. During my venture, I did find the #6 injector clogged and is now replaced. This never showed why my wideband showed lean condition.....that's because the wideband is located on the driver's side/odd cylinders. Finally, after I got everything back together....everything was the same.....LEAN. Finally, I thought it could have been my wideband O2 lying to me. I ordered a new one and replaced it. WHA-LA!!!! Batta Bing Batta BANG! That was my whole problem!!! My first initial thought had to be the last thing I tried....replace the wideband O2. However, I would have NEVER found the #6 injector problem if I had not went thru this thing very thoroughly.

I want to thank everyone here on thier participation in helping me get this thing fixed. I wouldn't have got this far without your help. THANK YOU.

As far as it goes with the injectors being too small???? I plan on changing these things out ASAP and going with at least 38 lb injectors.

 

It's good to see that you stuck with it and got it fixed! I'm also glad that you updated us since I can now stick your results into my book of problem solving steps.

 

yes go with at least 38lb injectors, whats your current or future HP goals, maybe I can help you select an injector.


also, I'm very glad you solved your problem BUT why do you ONLY have your wideband located in the ONE side of your exhaust (one header)???

why not put it in the I pipe or somewhere else in the exhaust stream?? you will not see a A/F difference