Still pinging w/Howell and TFI. Need HELP.......

TOM85CJ7 · #21 01-20-2003, 06:43 PM

Plugs are white. Power is decent, comparable to other 258s I have driven. I think that the TBI is lean at 1800rpms and above. I clamped the fuel return line again which should richen the mixture according to Howell. It still pinged. I installed new Champion plugs gapped at .046. I will run them a while and then possibly try a colder plug. I am content to let it ping assuming it isn't causing any major damage to the engine. Does anyone think that the MSD 6 will have an effect on detonation? I don't see how it would help, but someone suggested it. What about the RV cam?

Later,
Tom

#22 01-20-2003, 08:57 PM

"13. This way I can easily monitor the TFI anytime"

Is this what you meant to write, LEVE? you lost me. TFI=thick film ignition?

LEVE · #23 01-20-2003, 09:02 PM

opps... I meant the TBI....and how it's dumping fuel into the manifold... [img]images/graemlins/blush.gif[/img]

TiminMb · #24 01-20-2003, 09:02 PM

White plugs indicates too lean of a mixture or too hot of a plug. If you are using the right plug, then it's got to be indicating too lean of a mixture. How does the plug recommended by Howell compare to the stock plug??

I see no impact of using MSD on the pinging situation. Should do no harm either. You can buy a nifty timing advance / retard gizmo for your msd so that you can adjust timing on the road. Might be handy for towing or other scenarios where the load is increased significantly.

Clamping the return line will boost the pressure the injectors and increase their flow for a given pulsewidth (doubling the pressure increases flow by 50%, it's not linear) of opening command. I assume they don't mean clamp it shut. That would be way over pressure. Pressure would match the cutoff limit of your pump. Gm tbi's run at approx 13 lbs/ square inch fuel pressure. Electric fuel pumps, depending on their intended use can generate 50-100 or more psi depending on their design. If that solved your problem, you could alter the spring tension on the internal fuel pressur regulator. There's info on the net on how to do this by modifying the plate behind the spring. Problem is, wouldn't closed loop operation simply result in the ECU cutting down the injector opening time to compensate for the increased richness. If the ECU's not regulating the pulsewidth right now based on 02 sensor input, then why isn't it?? In other words, why isn't the information provided by the 02 sensor of the lean condition not resulting in the ECU enriching the mixture???

It's interesting that the problem occurs once the engine warms up. Closed loop operation, that is using the 02 sensor to control mixture, doesn't cut in until the engine meets a certain temperature.

Have you told Howell that your plugs are white? Curious what their response is to a potentially too lean of mixture. Hope they give you good tech support.

Leve had some good suggestions on how to read the ecu's 02 sensor data from the diagnostic light. See if it indicates too lean.

#25 01-20-2003, 09:27 PM

Are you using the MSD with the Howell EFI?

I believe that is the way I read your post. I had the MSD6A on my 258 along with the TFI coil prior to having the Howell installed. At the time of installation I had to remove the MSD6A and revert to the original ignition module, still keeping the TFI coil and rest of the TR Ignition upgrade. The reason (though it was some time ago and is a little fuzzy now) was that I needed some type of connector or other from Howell so that the MSD worked properly with the Howell set up. I cannot recall exactly what it was but Howell suggested at the time to go back to the standard module. Of course this may have no bearing on your problem but thought I'd "inject" it. - I'll try to find my notes. John

Frosty · #26 01-20-2003, 10:59 PM

I'm sure you've already checked this, but I didn't see it mentioned. Have you verified TDC against the mark on your harmonic balancer? If it has 'slipped' you could be getting more advance than your timing light indicates.

in2mud · #27 01-20-2003, 11:32 PM

I'm not familier with the Howell system but I'll put in my $.02 worth anyway.
Where you able to moniter the O2 voltage with that scanner as it was pinging to see what it was reading?

Does the O2 have good cross counts (above & below .5 v) It should keep varying above & below it shouldn't hang on 1 voltage in closed loop.

Do you have access to a advance type timing light to see what your total advance is and if its smooth in getting there?

2 ways to trick it to richen the mixture and see if it stops pinging but it takes 2 people to do it safely because I take it you need to be driving for it to show up.

1. Hook up a hand vacuum pump to the map and pump it up to normal vacuum reading while crusing when it starts to ping release the vacuum it should richen it up somewhat before it goes into limp mode. You could also check the map this way to see if the voltages are smooth and could also sweep the TPS but the problem is most meters won't catch a glitch unless you spend lots a $$$$. It could be 1 of your many sensers has a "lazy" spot but not enough to set a code just because they are new means nothing.

2. You have to splice into the O2 wire then hold that wire in 1 hand and touch your other hand to a 12v - this will tell (force) the computer into thinking its lean and it should richen the mixture. You can also touch a 12v + to go the other way these should both be direct to the battery or perferably a 10 g wire direct to the batt. DO NOT TOUCH THE WIRES TOGETHER or you'll fry the computer the O2 puts out milli-volts so you need the resistance of your body.

I've done both these test before on GM & Fords so they should work on Howells system.

#28 01-21-2003, 03:08 AM

Well, i don t know much about the Howell TBI but, if it use a GM ECM, it is kind off like my setup.
My first start was crap, bad idle, died when cold, pinging... My dist is controlled by the ECM and so, the only way to tune all this is to burn Eproms for the advance and the fuel map. I have already tried 5 different seting and now i am almost done...
I am not very good at it yet and have still to learn a lot,but, maybe you should ask Howell to send you different Eprom to see if it gets better with one or the other or, programm them yourself if you think you can do it... Every engine is different (custom intake, header, cam...)so every Eprom for TBI setup should be too...
Good luck...
PS: I only burn them, the .BIN file is writed by J.W from www.customefis.com . One day i ll understand everything about it, i hope lol

TOM85CJ7 · #29 01-21-2003, 08:51 AM

Howell doesn't recommend any specific plugs for the kit. The standard plugs and gap should work. The Howell kit is designed for a stock Jeep 258. Any deviation from that might be the cause of my troubles. I am going to revert to the original ignition configuration. I assume that the TFI coil puts out significantly more spark and would make the plugs "hotter". If that solves the problem, then I know the limitations of the Howell kit. Does anyone think that the TFI isn't a factor?

Thanks,
Tom

PS While I had the Jeep hooked up to the "Analyzer", I reviewed all of the sensors. Everything was in line with what Howell said. I believe there kit is working as intended, however it is not working well on my engine.

LEVE · #30 01-21-2003, 09:01 AM

1. I run a GM HEI on my Howell System.
2. It's hotter spark does lend to a better combustion of fuel.
3. You'd think that woul make the engine run leaner...
4. However, this is stll within the ECM's ability to adjust for,
5. Without any Eprom adjusts.
6. IMHO, the TFI would be the same...and
7. No adjustmets would be needed to the Eprom.

I agree with you assessment that the cam may be the problem...