Expert TBI Assistance Needed

[bkshir]

Hello,
I would first like to say thanks for all the helpful information posted here on this forum. I recently installed a TBI system on a 350 SBC and I am having a few issues with it. It is in Jeep CJ7 (sorry) but anytime I search the web for answers related to TBI conversions, I keep ending up back here (usually on a thread where Bill usn-1 has offered valuable input regarding the subject). So, I was hoping maybe I could get some input on a few issues I am having.
Here are the basics on my setup:

1. Older model SBC 350 circa 1978.
2. Manual transmission (no speed sensor)
3. Dual plane aluminum 4BBL intake manifold.
4. Shorty block hugger headers with heated O2 sensor in collector.
5. Possibly a mild low end torque (RV type) cam. I didn’t build the engine.
6. Wire harness and PROM from Howell EFI Inc.
7. 7747 ECM, TBI, Dist, ESC, Coil, MAP, CTS, Knock Sensor, Fuel lines, Air Cleaner from running 1990 Chevrolet P/U, 2WD, 5.7L, Auto.
8. Walbro GSL395 frame mounted fuel pump.

Howell was supposed to burn the chip for my setup. I haven’t gotten any DTC’s so they seem to have that much right, but it cuts out and runs really choppy when it’s cold. Once it warms up, it runs a lot better, but it will cut out sometimes when I go WOT. It also won’t idle down after it has been driven. It hangs around 1700 RPM. I checked for vacuum leaks and base idle is good. ECM just seems to command the IAC too high once it has been driven. The idle starts out around 1100 RPM. Howell says that’s because they bumped up the idle in the chip. Seems a little high to me, but the real issue is the 1700 RPM idle after I drive it a little. I used WinALDL to capture some data which I will try to upload with my post. If anyone has any ideas, I would be glad to hear them. Thanks in advance.
Bill

[Bill usn-1]

I wondered how all the jeep and toy and chevy guys kept showing up here.
And there are no experts I know of here.

I see 2 main problems right away.
first your log shows you are in park all the time so your wiring is not right.
second-you haven't performed the initial set up procedures.
Fix those 2 and then log some more.

[bkshir]

Thanks Bill. I assume you are referring to the TPS readings when you say I need to do the initial setup. That's the only part I haven't done yet. I will just need to file out the mounting holes as you state in the instructions. Fuel pressure is about 14.5 psi (just a tad high). I have tried the base timing at 0 and then 5-6 and even at 10-12 as recommended by Howell. It was about 6 during my data collection. Base idle is around 500-600 rpm.

As far as the wiring goes, I haven't touched the harness since I received it from Howell other than plugging it in and connecting power leads. I will see what I can figure out with the continuous park signal issue though.

Thanks again,
Bill

[Bill usn-1]

Yes, TPS is way off so the ecm does not enter idle mode.

Since you have some lean and some rich areas in your fuel I was not worried about the pressure.
If it all goes rich when it's running right then it can be addressed.

[bkshir]

Cool. I'll get that TPS adjusted. So, isn't the Park issue something that Howell should have addressed? I told them I was running a manual transmission. That is kinda disappointing. I paid good money for them to make that harness plug and play for my application.

[Bill usn-1]

Easy to check the diagram in the FAQ.
IIRC it's B10.
You would think there would be no wire there if you said manual.
If there is a wire then make sure it is not connected to anything.

The chip you have was based on a 5.7 auto-ARJT

[EagleMark]

Originally Posted by Bill usn-1

And there are no experts I know of here.

You are seriously underestimating your abilities!

[bkshir]

OK. I adjusted the TPS to .59 volts or 1.7% at closed throttle. Attached are the data logs from the test run that followed. Didn't seem to change much but at least it is set properly now.

[bkshir]

I also looked into the issue with it always showing to be in Park. There was a wire connected at Pin B10 in my Howell harness that was providing ground at all times. I didn't trace it down, but I did remove the pin from the connector and tape it up and zip tie it along side the harness. I was running low on gas and time, so I took a short test run around in the field near my house. It immediately started idling lower. I lugged it down to the point that the IAC was running pretty much wide open and then pushed in the clutch. The RPMs flared up as you would expect, but then it settled back into an idle around 750-800 RPM. That is when it would have normally continued to rev around 1750-1800 RPM. So, that seems to have made a huge improvement. Thanks Bill!!! I will have to test drive it some more when I have time, but it is definitely getting better. I have attached a short LOG file of my test run. Thanks again for your help.

Bill

[Bill usn-1]

Good progress.