Did TBI mods and spacer today. Now truck dies upon accel from idle. please help?

[Nobodys94]

Its my 94 5.7 TBI truck. Mods before TBI work 3:73 gears, 4l60e trans with vette servo, shorty headers and electric fans.

I did the ultimate TBI mods today, trans dapt 1" TBi spacer and the 1/4" injector pod spacer.

Exact rundown of what I did to TBI, removed ridges, radiused bores and cut down throttle blade shaft by 50%. Added TBI spacer and injector pod spacer. I used INj pod gasket on both sides of pod spacer. Removed the breather spacer.

My truck had no issues before this, now at low speed (basicly idle in gear)when I give it 1/4 throttle or more it hesitates and almost dies then picks up. Too much throttle and it dies. Does not do it in park or reverse or when I punch it at highway speeds. In park or neutral it revs fine, and in reverse it will dang near snap your neck. No check engine light or anything else. Truck pulls much much harder now too and I can tell a huge difference in throttle response.... Truck idles better and starts quicker as well..

I didnt readjust timing or tps. Reinstalled IAC the same from I pulled it out.

Gotta get this fixed asap. please help me trouble shoot this?. Thanks.

 

[95Escahoe]

You didnt need to put the gasket on either side of the injector pod spacer should say that in the instructions, back to your question I did the same thing minus TBI spacer and it runs mint, did you un hook the battery to reset it? And did you do the quarter mod to bump the fuel pressure up maybe its a fuel issue, check it all again and make sure everything is attached and the TBI unit is on tight

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[Nobodys94]

I dont know about the quarter mod? I think I had seen some post about it but paid it no mind. I also didnt know I needed to reset the computer too? I was wondering if maybe the gaskets had spaced the inj pod too far away or maybe it is a fueling issue as it seems to act lean. I will dble check it all tomorrow and see about the quarter mod as well..

I did not remove the tps when doing any of this and also wondering if I got the IAC in all the way?

Thanks for the response...

 

[95Escahoe]

I dont know about the quarter mod? I think I had seen some post about it but paid it no mind. I also didnt know I needed to reset the computer too? I was wondering if maybe the gaskets had spaced the inj pod too far away or maybe it is a fueling issue as it seems to act lean. I will dble check it all tomorrow and see about the quarter mod as well..

I did not remove the tps when doing any of this and also wondering if I got the IAC in all the way?

Thanks for the response...

Quarter mod bumps the fuel pressure up a lil goes under spring in regulator, ya you deff gotta disconnect battery and let it reset, ya u dont need the gaskets at all, how old are both sensors? When I did mine I pulled them they were only a few wks old cause you cant clean it that good with them in, did the mods, spacer, and new injectors and runs mint no issues

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[James Hart]

my truck is doing this too... only thing I did was put a universal EGR value from autozone and replaced the vacuum lines. My assumption is the EGR valve isn't working properly (as per lots of web searching). I'm planning to replace it with a Delphi one next week.

[Edit] never mind, I reread your post... mine is ONLY doing this off idle and for slight speed increases while cruising. giving it a bunch of throttle and the thing goes fine. [/Edit]

 

[Nobodys94]

just pulling the neg cable off is good enough to reset it?

 

[Yeti_Owner]

Woah...slow down cowpokes...

Fundamentals:

Make sure your MAP sensor is plugged in, and the vacuum line is connected.
Make sure ALL vacuum lines are plugged in correctly, and not leaking.
Make sure you have NO vacuum leaks.
Make sure ALL grounds are connected.
Make sure ALL sensors are connected.
Get out a multimeter, and test voltages and operation: coolant temp sensor, MAP sensor, throttle position, and o2 sensors. Autozone has a "how to" on this, just create an account and enter your information. Don't start jacking around with the FPR until you've eliminated the obvious.

All of the above can be done in less than 30 minutes.

Let me know what you find.

 

[Nobodys94]

got the neg cable off now, gonna pull the breather and check everything. Its extremely windy today making it kinda cold.

Thanks everyone, will post back in a few.

 

[Yeti_Owner]

Coolant Temperature Sensor (CTS):

Coolant sensor approximate resistance specifications:
177 ohms @ 212 deg. F. or 100 deg. C.
241 ohms @ 194 deg. F. or 90 deg. C.
332 ohms @ 176 deg. F. or 80 deg. C.
467 ohms @ 158 deg. F. or 70 deg. C.
667 ohms @ 140 deg. F. or 60 deg. C.
973 ohms @ 122 deg. F. or 50 deg. C.
1188 ohms @ 113 deg. F. or45 deg. C.
1459 ohms @ 104 deg. F. or 40 deg. C.
1802 ohms @ 95 deg. F. or 35 deg. C.
2238 ohms @ 86 deg. F. or 30 deg. C.
2796 ohms @ 77 deg. F. or 25 deg. C.
3520 ohms @ 68 deg. F. or 20 deg. C.
4450 ohms @ 59 deg. F. or 15 deg. C.
5670 ohms @ 50 deg. F. or 10 deg. C.
7280 ohms @ 41 deg. F. or 5 deg. C.
9420 ohms @ 32 deg. F. or 0 deg. C.
12300 ohms @ 23 deg. F. or -5 deg. C.
16180 ohms @ 14 deg. F. or -10 deg. C.
21450 ohms @ 5 deg. F. or -15 deg. C.
28680 ohms @ -4 deg. F. or -20 deg. C.
52700 ohms @ -22 deg. F. or -30 deg. C.
100700 ohms @ -40 deg. F. or - 40 deg. C.

Manifold Absolute Pressure Sensor (MAP):

Check the reference voltage supply at pin C of the MAP sensor (gray wire typically).

Measure voltage between pin A (ground) and Pin C (+5 V ref) with a DVM. It should be right around 5 Vdc.

With Key on engine off the MAP voltage (Pin B, light green wire typically) should read around 4.8 to 4.9 volts. If it reads the same as pin C the sensor is probably is history.

Also check ground reference pin A. With everything off, measure resistance between Pin A and electrical ground (stud next thermostat). It should be fractional ohms

Idle Air Control Sensor (IAC):

1. Disconnect the negative battery cable.
2. Test resistance between terminals A and B, then test between C and D.
3. If the resistance is nor 40-80 ohms, replace the IAC.
4. Connect the negative battery cable.

Throttle Position Sensor (TPS):

Test between blue and black wire.
.5v idle to 5v WOT

 

[Yeti_Owner]

Trying to find something with pictures of the pinouts.