Forerunner engine running issues, please help, it's a long tale.....

Submitted: Tuesday, Dec 23, 2008 at 11:21

ThreadID: 64508 Views:2814 Replies:9 FollowUps:3

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Troosty (WA)

Hi Forumites,
Recently I purchased a 1992 V6 Forerunner on petrol / gas, the vehicle was a bit "lumpy" when I bought the vehicle so I decided to investigate to a point now where I'm at my wits end. Three garages have had a look at it all giving varying solutions none of which have improved the running.
I've now got to a point where I've replaced the distributor, the engine now runs really well but when the engine is revved quickly when the engine comes back to idle it cuts out. If the engine is let back to idle slowly everything is fine, idles perfectly.
I'm not sure if any adjustments were made to other things to compensate for the dodgy distributor, does anyone out there have any personal experiences with some such problem, this is only at the moment being run on petrol to get that right first before playing around with the gas system.
I've been given all sorts of answers such as fuel pressure sensors, fuel pumps, timing which I can't seem to adjust. Which wire do you disconnect from the distributor to take the computer out of the loop so I can set the timing manually? I know one has to be disconnected so without cutting each wire until I hit the right one does anybody know.
If people who have constructive comments could respond it would be really appreciated, buying another brand of vehicle isn't in the plan, I've just got this one and I like it for all it's woes.....
Thanks in anticipation for any responses that lead to a solution.

Merry Xmas and a Happy New Year.

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Reply By: Mark Taylor - Tuesday, Dec 23, 2008 at 11:45

Tuesday, Dec 23, 2008 at 11:45

Hi there.. don't know if this will help..

I had an 89 SAAB Turbo 900 that used to do this.. I was an auto and would die just like you describe. Drive me nuts.. my wife was terrified of it. Usually stopped halfway through a slow corner turning onto a railway bridge on the school run and left you with no power steering.

I am not a mechanic.. but was an auto electrician and did all the distributor stuff at tech etc. So I thought it might have been a vacuum leak.

Well.. I bought a roll of vacuum hose from Repco and replaced every bloody vacuum hose on the engine.. and there were bloody millions of them. Just unlpg the hose at one end, run the new one through and plug it in at the other end.

When I finished.. fabulous.

Problem solved.

Neve did find out which hose was faulty.. but this solved the problem.

You can actually buy a hand held vacuum pump with a gauge to check for leaks.. but i figured it was all getting on so replaced the lot.

Cheers

Mark Taylor

AnswerID: 341040

Reply By: Mikelb - Tuesday, Dec 23, 2008 at 13:06

Tuesday, Dec 23, 2008 at 13:06

For timing, the manual states:
Disconnect vacuum hose from distributor and plug the hose.
Use a wire (bent paper clip) connect E1 and T on the check wiring plug
With your timing light set advance to 10 degrees plus or minus 1.
Some distributors need a special spanner to loosen the distributor, mine I can just use a socket.
I bought my 91 model 6 weeks ago and had a similar problem when starting a hot motor. The engine would idle down and stall. It needed to be revved up to settle it down. I had the spark plugs changed to Platinum and the throttle body decoked. I have also run 2 tankfuls of petrol run through with half a bottle of Nulon petrol injector cleaner in each tank. At this stage all seems to have settled down

AnswerID: 341048

Follow Up By: toyocrusa - Tuesday, Dec 23, 2008 at 21:22

Tuesday, Dec 23, 2008 at 21:22

This is the most sensible answer to enable you to do it yourself.(The "check wiring plug" is actually the diagnostic terminal under the bonnet.Should be on the passenger side) Once the timing is set you need to check the butterfly in the throttle body is set correctly. You can then adjust the idle speed with the air screw which is on the throttle body. Regards, Bob.

FollowupID: 608833

Reply By: Rod W - Tuesday, Dec 23, 2008 at 13:44

Tuesday, Dec 23, 2008 at 13:44

Take it to a reputable service mob who can hook it up to a computer and pin point the problem.

AnswerID: 341054

Follow Up By: Martyn (WA) - Tuesday, Dec 23, 2008 at 13:54

Tuesday, Dec 23, 2008 at 13:54

Rod W,
I've been following this through with my mate here, he's taken it to Toyota who you would think have all the right gear to sort this out, they kept the vehicle for a whole day with no resolution, weren't that interested. Unless something is permanently broken the computer won't pick it up apparently.
Anyway appreciate the input and you're right this should be the answer but in this case it isn't. My mates had more success having a go himself, the new second hand dizzy has made things 99 % better but not perfect, only the idle is now the issue, I suggested the forum to him, and by the looks of things he's already getting answers that help move things forward. At the moment the timing mark won't move when the distributor is moved, the computer is compensating, need to disconnect the computer to get the mechanical setting right. This one doesn't have a vacuum hose so that's out.............
Thanks for the response.

Keep the shiny side up

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FollowupID: 608742

Reply By: MrBitchi (QLD) - Tuesday, Dec 23, 2008 at 14:20

Tuesday, Dec 23, 2008 at 14:20

Find yourself a good performance shop with a good dyno operator. A problem like this should be able to be fixed on the dyno.
If you were in Brisvegas.... Don't know anyone in WA.

AnswerID: 341059

Reply By: Member - Olcoolone (S.A) The O - Tuesday, Dec 23, 2008 at 16:17

Tuesday, Dec 23, 2008 at 16:17

Have you checked the oxygen sensors, one may be faulty.

A faulty oxygen sensor will cause what you are experiencing, but will not show up as a fault.

AnswerID: 341084

Reply By: chevypower - Tuesday, Dec 23, 2008 at 18:09

Tuesday, Dec 23, 2008 at 18:09

Isn't it 4Runner? 4 as in "Four" not "Fore"

AnswerID: 341110

Follow Up By: Member - Ian W (NSW) - Wednesday, Dec 24, 2008 at 19:49

Wednesday, Dec 24, 2008 at 19:49

Good question Chevypower,

Good very well mean the difference between fixing or burning.

FollowupID: 608935

Reply By: young_codger - Tuesday, Dec 23, 2008 at 18:09

Tuesday, Dec 23, 2008 at 18:09

I've got a petrol/LPG 2.7 Hilux that had similar problems.
Get your LPG system tuned (mixtures), as it could be out of wack (pretty cheap).
If it still runs the same, check your airbox for holes or a bad oxygen sensor.

AnswerID: 341111

Reply By: trainslux - Wednesday, Dec 24, 2008 at 10:57

Wednesday, Dec 24, 2008 at 10:57

Two things I would offer you to look at, and apologies if you have already done them.

First, clean your throttle body, and idle step motor. Not sure if the idle up motor just adjusts the air bypass the throttle butterfly, or if its a physical opening of the butterfly.

check these 2 and any obvious vac leaks as already mentioned.

This is quite a common problem on efi vehicles.

get it running right on pet, then tune gas to suit.

Trains

AnswerID: 341187