Car Keeps Dieing And Can't Figure Out Why?

[j3ffr3y]

I've went through everything I can think of to try and figure this out but I'm completely stumped.

I have a 1993 ES300 V6. I'm getting tired of working on this thing so I really need help figuring this out. I do NOT have enough money to pay a garage to find and fix it for me so I'm doing this all myself.

I would appreciate any input so I can make a list of things to check. I would also appreciate it if I could get a "How to" on whatever it is I'm checking.

Here's my issue:

It is very hard to start at first but after at least 10-20 tries, it finally does and it will idle. As soon as I try to give it any amount of gas (ie... pressing the pedal even slightly) it dies.

Here's what I've done so far.

Changed head gaskets

Timing belt

Water pump

MAF

EFI (SFI main relay).

I have done the test for the fuel system by connecting terminals +B and FP of the data link connector 1.

Cleaned everything I can think to clean in and around the throttle body and replaced everyt gasket there was on it.

Checked the hoses and they all look good and/or if they didn't, then they were replaced.

A year ago I had the fuel filter and injectors changed so I'm guessing those are still good.

The spark plugs are fairly new.

I had a problem about a year or so ago with the ECU so I had a rebuilt one put in.

I checked each spark plug and wires for spark.

Checked for fuel again by taking the hose loose from the cold start.

I can only think at this point that it has to be one of these things but I'm not sure how to check them.

The distributor cap looks okay but it has a tiny chip on one side next to one of the screws.

The TPS, not a clue what I'm looking for to check on it to see if it's working.

The fuel pressure regulator.

The opening circuit relay.

Or the ECU has gone bad again.

I'm sure I probably left out a few things somewhere. I just REALLY need help figuring this out. I'm getting ready to move and it needs to be fixed SOON!

[lexis lexus]

Impressive amount of work. You've covered 2/3 basics -- spark and fuel. I frequently don't like to ask the question if I don't want to know the answer, but....have you check the compressions?

The throttle position switch adjusts the opening of the butterfly in the throttle body at idle. Have to measure resistance across the contacts, under various clearances between lever adn stop screw as follows (taken from pdf FSM 92-96):

clearance / between terminals / resistance (k ohms)

0mm / vta-e2 / 0.28-6.4

0.35mm / idl-e2 / 0.5 or less

0.70mm / idl-e2 / infinity

throttle wide open / vta-e2 / 2.0-11.8

" / vc-e2 / 2.7 - 7.7

the contacts in the open connector are in this order: vc, vta, idl, e2

Another thought has to do with the cold start injection device, but I know next to nothing about that, just the name and its suggested function which isn't (i.e. cold starting) in your '93.

Hope this helps.

LL

Edited October 9, 2010 by lexis lexus

[j3ffr3y]

Thank you for that reply.

I've just re-checked the timing, just to make sure and for peace of mind I suppose.

I have not checked compression as of yet. My friend has a compression gauge but he keeps telling me that it doesn't "act" like it's a compression issue. However, I think I'm going to do that next anyway. Again, just to make sure and for peace of mind.

As for the cold start, I took it out and cleaned it thoroughly and as much as it could possibly be cleaned, then put it back in. I didn't think that would fix the issue of it running when I give it gas but another "just to make sure".

The TPS specs that you have are the same as what I have seen in the manuals that I have but I have no idea what I'm doing with the ohmmeter. I guess I will have to start learning how to use one or at least the one that he has in his garage.

I will post again after I've done the compression check. Hopefully that isn't the issue because I really don't want to have to take the head back off again. LOL

Thanks again.

[j3ffr3y]

Update:

Just finish the compression check. The specs show they are supposed to be between 142 minimum and 178 max. I've got 165 to 178. Soooo it's not the compression.

Just out of curiosity, I checked the plugs again so that I knew the plugs and wires were okay at least. Each one of them fired but a couple of them were kind of an orange-ish color and not white/blue like I've heard they are supposed to be. They are Bosch platinum plugs. The manual says that this vehicle runs best on platinum tipped plugs. So my question is, is there something wrong with them or could it be the distributor cap?

I'm going out now to check the TPS with the ohmmeter. My friend has shown me how to use it and I can at least try to get the readings now.

Anyone who has any other input is very welcome to comment. I would really appreciate any insight I can get.

Thanks!

[dcfish]

I would replace the Bosch plugs with denso OEM plugs

[j3ffr3y]

Will certainly change the plugs. Thanks DC! I was actually planning on doing that but I can't seem to find anyone that carries Denso around here. I found the NGK and Autolite but that was it other than the ones I have now.

I checked the TPS but it is giving some really weird readings so I've decided to replace it anyway. I found one that is tested and warranteed on ebay for $30 so that should be here at least by Tuesday.

Should I check anything else in the meantime? My friend did some kind of check while I was gone and he keeps telling me that I'm getting fuel but it's not enough to keep it running. Could the TPS be causing that or should I be looking elsewhere for the problem?

[lexis lexus]

fuel pump?

LL

[j3ffr3y]

Knew there was something I forgot to mention. I did the check as it was in the manual by bridging the +B and FP circuit on the diagnostic box. I could hear the fuel pump and the injectors. From what I understood, there was no reason to suspect the fuel pump. Was I wrong in assuming this?

[LoveLearn]

Downstream from your injectors is your little stepper-motor powered air control valve which the engine management computer manages. Most people assume that everything that's in gasoline is extremely volatile so when it is sprayed, forming lots of tiny droplets into a quick-moving air flow, nothing sticky will be left behind. Sorry to rupture that balloon, but in fact evaporating gasoline leaves a small but continually-building condensed layer of very sticky varnish-like film. This layer of gasoline precipitate can and does eventually increase the shaft friction on that stepper motor controlled valve so much that computer pulses can no longer spin the stepper motor against that increasing friction. When, not if, that happens, these engines develop the symptoms you've described.

Spray solvent without removing for a more complete cleaning may be enough to restore operation for a while. But a really good solvent cleaning off the engine may be required.

Shop owners who are eager to generate shop income tend to suggest replacing these units is the only "correct way" to restore them to like-new operation.

There's the car owner, the shop owner and the part vendor's interests at stake. This strategy is good for the shop owner, good for the part vendor (which may be the shop),

and "two out of three isn't bad." Not a good economic decision for the car owner who only needs that gummy gasoline precipitate dissolved away.

A quick spray solvent clean-up every 60,000 miles or so should prevent these symptoms from occurring.

More non-conventional advice from me.

John