Throttle Body

Welcome to the board. Nothing constructive to add, but here are some handy abbreviations for our enigne discussions:

AFM = air flow meter
TB = throttle body
CS or CSI = cold start injector
TPS = throttle position sensor
VSV = vacuum switching valve
ECU = electronic control unit, aka, "the EFI computer"

That'll get you going...

I was in the same boat. When cold it was hard to start like you mention and ran bad for a minute, as soon as the motor warmed up all was well.


I cleaned up the connection at the water thermo sensor and the cold idle smoothed out instantly.
My guess is I had too much resistance at the connector. sensor tested good...

First, tks for all of your input.
Now some feed back on where we are.
1) The spark plugs have about 6K miles on them and they were installed by SNVA Toyota so I assume they are nippondenso (spelling?).
2) The spark plugs wires, rotor and rotor cap are all original if my memory is correct.
The wires look like new.
The rotor cap seems good although showing some "arc-erorsion on the inside terminals. If someone knows a good measure for good/deteriorated I would appreciate hearing what it is.
The rotor shows no visible arc-erosion and looks ok. I am not sure how one would remove it. It is firmly attached and my manual shows no removal clues.
3) I ohm-tested my air flow meter (AFM) and the
E2-Vs test failed giving a reading of infinity. All other tests were ok.
4) I performed a diagnostic test on my ECU and received diagnostic codes of 2, 5. 8, and 10.
One of the no. 2 code option explainations (Vs-E2 short circuited) matches the AFM error above seeming to confirm a AFM defect. Although I must admit the ohm reading of infinity and the words "Vs-E2 short circuited" apear contradictory.
The diagnostic code no. 5 is for my Ox sensor signal. I am due for a new sensor and will revist this after deleting the codes and taking a relook.
The diagnostic code no. 8 is for "open or short circuit in intake air thermo sensor signal". I assume this sensor is something inside of the AFM. Here they use the "open or short circuited" language which seems contradictory to me but does match the Vs-E2 infinity reading and the no. 2 diagnostic code language of "short circuited."
The diagnostic code no. 10 is for a started signal which I will explore later.
PATH FORWARD: Unless I hear something brilliant from a reader I expect I will have to eat the cost of a new air flow meter.

If I recall, you can bypass the AFM by jumping the two brass looking terminals in the wiring harness. you prabably still need to keep the AFM hooked up to the T.Body.

I'm going to go with a vacume leak somewhere. When I had a vacume leak, the truck would start, then sputter then idel fine. It was a small leak, so if you have a bigger leak I would imagine it would start, then stall out. But it did start fine once warmed up.

Uh no I do not think so...<img src="/forums/images/graemlins/mrt.gif" alt="" />


New AFM are around $500 IIRC, so before you buy a new one....
Make sure your ECU is not shorting out.
Check the connectors at the ECU for moisture and or corrosion.
Many ECU's including mine were affected by a leaky windshield. Some replace them, others open them up and clean the printed curicuit board.

I would at least open up the cover to the ECU and look to see if the board is clean.


good luck and keep us posted

my guess would be a leaking injector that is letting the pressure out of your fuel rail.
if your truck has been sitting for a few hours you can crack open the brass looking 12 mm screw that feeds your cold start injector there should be pressure there.
oh.. not running..

tks for the comments.
1) OK, GOI87, where was your vacuum leak and how did you solve it?
2) I'll take a relook of the boots between the air flow meter and the throttle body. I may have missed a hairline crack.
3) I'll inspect the ECU for any evidence to pursue.
4) The term "rail" (Staceman, 9-22,10:02)and/or "fuel rail" (Missouriman, 10-01, 12:00) have both been referred to now. What is it? Looks like?
If I crack open the brass looking 12 mm screw that feeds my cold start injector and there is no pressure, this symtomatic of what and means what?
5) IIRC = ?__________?

4. Rail = fuel injector rail, the thing the injectors and fuel pressure regulator and pulse damper are attached to, under the intake plenum.

No fuel at the CSI = no residual fuel pressure. Try the fuel pump test jumper:
- http://www.4crawler.com/4x4/CheapTricks/index.shtml#FuelPump
5. IIRC = If I Remember/Recall Correctly.

I said IF I RECALL. This was brought to my attention while at the junk yard. I haven't tried it, no do I know someone who has. Give it a shot, what do you have to lose?

I don't recall where the vacume leak was, all I remember was that a small hose came off towards the back of the Intake.

If the truck Runs once it is running then I would rule out the ECU. If the ECU is bad then the truck wouldn't run at all.

Sound to me like you have a disconnected vaccume line or a fuel related problem, like messed up/clogged injector(s)

GL <img src="/forums/images/graemlins/kewl.gif" alt="" />