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I got a deal on a Howell system a while back. It is the CARB version and is missing the o2 sensor/bung and VSS. I talked to Howell and they said if I'm not in California I don't need the VSS but I've been reading and it seems there may be some advantages in having one hooked up. So I figure I'll get the VSS and hook it up.

Question #1- It is wired for a 4 wire O2 sensor but the plug is melted and needs replaced. Is there any advantage to using a WB sensor over the cheap regular 4 wire sensor?

Question #2- Does anyone know what VSS Howell uses and where else I can buy one (cheaper)?

Jags that run for the VSS, you want this one http://www.jagsthatrun.com/SpeedSensors_Order.html

You want the 2PRS $75 one top of the list.
I have 2 of them.

Unless you spend a bunch of money on more hardware there is no real way to get the WB info into the datalog w/ the 7747.
Just buy a replacement NB and fix the melted plug.
My innovate MTX-L WB can emulate a NB sensor, but it did not work well on the 7747 ecm.

Got it ordered, thanks

How important is VSS for our conversions? Is it something I need to do right away or can I add it in later? I've saved it on my harness. Also, would the 7427 use a the same 2 pulse VSS as a 7747?

Jason, you will want the VSS on your system (different than Howell). Use the same 2PRS from JTR.

For the stock Howell system, the VSS is nice to have, but may not be necessary.

For an O2 sensor, a Bosch #15510 O2 sensor will work. It comes with a dedicated plug, but I simply cut it and use my own weatherpack connectors. It's about $25. So far, the least expensive O2 sensor I've found.

As already mentioned, you can't use a wide band O2 on the 12277747 ECM.

Keep in mind that 2 completely different systems are being discussed here.

For the 7427 PCM you should run the VSS. Yes you can use the same inline cable VSS from JTR. 2PRS.
For the 7747 ECM it's optional (unless in CA).
You can run without it on the 7427 but it will take way more tuning then it's worth to make it right.

There are also 2 inputs F12/F13 on the PCM for the VSS input so if you pick the wrong one and don't read any speed you may have to swap it.

You won't use the VSSB. The VSS connects directly to the PCM. Should be F13 IIRC.

Fantastic, thanks guys.

Sorry for the thread hijack!

And there is a "switch" in the '7427 bin where you check off "VSS not fron DRAC" (DRAC is aka VSSB).

So, I'm on JTR's site and it's saying that the 2-pulse is for TBI up to '92. My ECU and harness are out of a '94. Will this matter?

I'll just email them, that should solve that too.

Some times you just need to trust us that have performed the conversion already.
The ECM uses the 2k VSS signal. The VSSB was used to convert the 40pulse signal into each signal needed. That is the 2K for the PCM.

LOL!

Yes, you DO want the 2PRS one. I have one sitting in my garage, actually. Ordered it last week and it arrived a few days later.

By checking the "VSS Not from DRAC" bit in the binary file, the PCM will read correctly.

Well do!

FSJ Guy wrote:LOL!

Yes, you DO want the 2PRS one. I have one sitting in my garage, actually. Ordered it last week and it arrived a few days later.

By checking the "VSS Not from DRAC" bit in the binary file, the PCM will read correctly.

Ethan, I really don't think that has any affect on it.
people just did it.

Since you have one sitting there, install it and toggle the setting back and forth and you can report back.
It may toggle between the TOS and the VSS input but I haven't verified it yet since once my systems were working i never went back to test other options.

If I had a Jeep to put it on, I would. LOL!

The VSS may not really affect fuel and timing, but for me it IS nice to have speed data in your data logging.

And supposedly for the 7747, the VSS lets the ECM know when the vehicle is moving vs. not moving. It must make enough of a difference for Howell to add it to their CARB compliant kits.

Are we discussing the 7427 or the 7747?
The CA emissions requires the VSS with the 7747 due to the EGR which is controlled by a speed table. It also is tied to the CCP if used.
So if running the 7747 in CA I set up the harness with the CCP/EGR and a 3 wire O2 which they also require to get it into closed loop faster.

But we were discussing the 7427 conversion and running the 2prs VSS.
You said you had one.

Yes, you DO want the 2PRS one. I have one sitting in my garage, actually. Ordered it last week and it arrived a few days later.

So i assumed with your discussion of how much better the 7427 is that your original VSS went bad and you are getting ready to replace it with the new one.
The 7427 uses many more VSS tables than the 7747 so it would be difficult to run one without a VSS without a lot of tuning.

Are you running the 7427?
Do you have a VSS hooked up?
just trying to figure out where you at with this.

Sorry to confuse you. I was talking about my previous conversion. I started with the 7747 and upgraded to the 7427. But I no longer have that Jeep. The VSS in my garage is for my next Jeep. I'm getting everything together ahead of time.

AFAIK, the Howell kit does not control EGR. I could be wrong, however.

Back OT to the OP's discussion, the VSS would be nice if you're tuning the system because you can turn on lean cruise and I suspect that it needs the VSS signal to go into lean cruise mode.

Wow. good information here. Thanks to all in the discussion. A couple of other questions come to mind. Is an EGR necessary (for TBI)? I have not read anything about it until now. I have a non EGR performer manifold.

Since I like to plan ahead... I know nothing about programming. When I am ready to swap the Howell ECM for one that can control spark should I go for the 47 or the 27? I already have a 7747 in a box somewhere (other than the Howell which is also a 7747)

Can someone speak as to the purpose of a knock sensor?

Mr. Goatman wrote:Wow. good information here. Thanks to all in the discussion. A couple of other questions come to mind. Is an EGR necessary (for TBI)? I have not read anything about it until now. I have a non EGR performer manifold.

Since I like to plan ahead... I know nothing about programming. When I am ready to swap the Howell ECM for one that can control spark should I go for the 47 or the 27? I already have a 7747 in a box somewhere (other than the Howell which is also a 7747)

Can someone speak as to the purpose of a knock sensor?

You may want to review thew parts required FAQ on the binderplanet.
I discuss each part and what is required and what is optional.

The Howell ecm is the same as your other 7747.
In fact the chip is the same.
Howell simply provides an inline tach filter to send to the ECM so it will still fire the injectors while you use the stock ignition.
So the only difference is in the wiring for the timing control and the distr set up.
Several guys with the Howell system have simply added the required wires for the timing control and modified the distr as described earlier.

Here's the main injection FAQs
http://www.binderplanet.com/forums/show ... hp?t=47254

Just click the link and then scroll down to TBI and click the parts required link.

The knock sensor is a protection device. It allows you to run a pretty agressive timing curve and if you get a load of bad gas or really hot thin air and the engine starts to ping, then the Knock sensor hears it and sends a signal to the ECM to tell it to retard the timing.
It's optional and not really needed but is nice to have a good working one if you do your own tuning.

You don't have one with your carb and it does ok, right?