odelrio

Hello,

I was wondering if someone understood the fuel cut rpm section of the FSM?

Page EG2-257:
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3. INSPECT FUEL CUT OPERATION
(a) Increase the engine speed to at least 2,500 rpm.
(b) Check for injector operating sound.
(c) Check that when the throttle lever is released, injector
operation sound stops momentarily and then res–
umes
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I've never been able to hear the injectors over all the other engine noises. Is there a trick to this?

BTW, the problem I'm trying to solve is that the RPM's will drop to 400-500 rpms when I come to a stop. It lasts about 3-5 seconds and then it pops right back up to 900 rpms. It'll stall every once in a while but usually it just stumbles and then catches itself. This is on a '94 4Runner (3VZE/manual).

Thanks for any help in advance!

Omar

abecedarian

One way to check for the 'injector sound' is to take a long ratchet extension and place the 'socket' end on an injector and the 'ratchet' end in your ear and listen for the clicking noises or use a long piece of 1/4-3/8" hose and do the same: one end on the injector, the other in your ear.

Also, check the TPS: http://www.4crawler.com/4x4/CheapTricks/TPS/index.shtml

toyota_mdt_tech

Ignore it. If yout TPS ias adjusted properly, you have fuel cut. Make sure the dashpot isnt sticking.

abecedarian

Hate to ask, but what is your basis for saying ignore it?

scuba

i would start buy checking that your tps is adjusted correctly

iamsuperbleeder

What brought fuel-cut into the equation anyways? My first though is that the dash-pot's sticking down as toyota_mdt_tech mentioned. If the little rubber boot type thingy has ripped off (like mine ), any kind of dust, dirt, or debris, and even a little rust from H2O, can get in there and stop it from working correctly.

Does it make any difference if the motor is cold or warmed up?

TPS maybe, but I wouldn't jump straight to it if it runs fine otherwise, especially if the idle comes right back to normal.

odelrio

While it's cold, it runs fine. Once it's warmed up, it's pretty consistent. The idle was originally at 750 and it would die regularly at stop lights so I adjusted it up to 900. Now it doesn't die but it still stumbles for a little while until it catches itself.

The background is I bought this 4Runner w/ a blown head gasket so I don't know what it drove like before the rebuild but I've had to troubleshoot a number of things since I rebuilt it. Yotatech was invaluable during this 3 month effort. One of them was a timing issue where I had no power and very bad gas mileage. The TPS was the culprit and I could then set the timing properly. This was about a month ago.

I've looked at the dash pot and it seems to be working. Moving the throttle, the plunger comes out and when I release it, it seems to dampen the return. If there's another way to check it, let me know.

That led me to the fuel-cut based on the FSM's description of what it does. I can have another look at the TPS though. I do recall having difficulty getting the feeler gauge to lay flat on the contact point. The access cocks the feeler gauge a little so maybe it's off...

Thanks for the help!