Author Topic: Figure me this....cranking, nearly catches, then stalls unless I hold the key  (Read 3089 times)

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Offline SSS

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So in the never ending quest of driving a 20 yr old car as a daily, the trx has started playing up.

I get back to the train station after work, car has been sitting in the unusual melbourne sun all day.

Engine cranks no problem, but wants to crank for another 3-5 secs before starting...during this time it wants to catch and run but doesn't. If I hold the key to start the normal period of time when it starts first go, it stalls straight away.

If it stalls, i switch the key to off, crank it again and it starts like normal.

Doesn't happen on cold mornings.

Idles and goes fine otherwise.

No codes in the ecu that i have been able to pull (so far).

First thing I will try is disconnecting the air temp sensor to default it to 20 deg C...I tend to think that it might heat soak during the day in the sun and be returning a faulty high temperature....which pulls timing back considerably.

Ryan, it's almost like the same thing that happened with your red trx that day at my place when your timing was at 0 deg BTDC, instead of 15 deg BTDC like it should have been.

Anyone else had this happen?

Offline Budgie

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I never happened to me with the car mate, weird problem tho!
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Offline SSS

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I have a feeling that the IAC valve might be on it's way out.

Offline Budgie

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I replaced that when I had the car after it threw up a fault code. Used one I had spare.
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Offline chr1S

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I know this is abit of a dig, my trx did this to me shortly after I built the motor, I had to unplug the ECT sensor plug and it would work every time, as soon as i connected it back up again, it would splutter to a stall. Strange thing is... I never changed the sensor, decided to plug it up again one day and it worked like normal.. lol.
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to be fair, it wouldn't be ANTRX if we stayed on topic.

and if someone wasn't cranky at Chr1s for something he said...

Offline SSS

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Yep...would have been intermittent contact.

I disconnected the AIT sensor which seems to have helped (ie, still does it on hot days, but kicks over and runs after turning the key only once).

I sprayed that CRC electrical contact stuff on the ECT sensor and terminal plugs a while ago, might need to give it another clean.

Problem is, because it happens pretty rarely these days, I don't have my laptop to check it with consult :(

Offline SSS

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Another summer down the drain....funnily enough, did not have this problem again even with the long run of 35+ deg days we had down here.

I have noticed though that it cranks longer when running BP98 as opposed to regular ULP.

Offline MattJohn

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Good to hear mate ^
Expect, longer whilst 98? That's unusual as!

Would anyone be able to riddle me this.. My car idles at 1000rpm. When I move the gear stick, NO CLUTCH, just move it any direction even whilst in neutral.. The car idle goes upto 1500rpm?

Offline Kranzy

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It's a feature of the KA. There's a neutral switch, when its in another gear it raises the rpm to assist in take offs.
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Offline SSS

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^ doesn't happen with either of my manual u12s.

If you are running an auto ecu in a manual u12, that will be it.

Offline Kranzy

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Mine has always done it. I had a manual ecu in manual car.

Can't remember if the sr20 does it or not.
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Offline Pure_Sincerity

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Mine did it, manual ecu with manual ka24e aswel. I never thought anything of it.
U12 TRX
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Offline SSS

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Something is not right then, you shouldn't see idle speed increase when you take the car out of neutral in a manual.

My Black U12 has never done it, my TRX has never done it. The other TRX I stripped didn't do it either. No other manual equipped car from other manufacturers i have ever driven have done so either.

Checking yesterday, both in and out of gear, my TRX idles at a rock solid 860-890rpm.

My Black U12 only had idle speed DECREASE when I put the car in gear when I used to run a modified auto ecu program, it did this because there was a table in the the program that would retard timing when it was told that the car was no longer in neutral / park. (this table is there in auto's to reduce torque output at idle, 1) so the car doesn't start driving off with the throttle closed when put in drive and no brakes applied, 2) when the brakes are applied, reduce the amount of work the torque convertor has to do to avoid unnecessary heating of the tranny fluid. This timing is generally dialled back in when throttle position is around 5-10%)

When I updated that piece of software which was then based on a manual trans ecu, no in or out of gear idle speed decreases / increases occurred.

It very well could have been a "feature" added in later models, I just find it strange since increasing idle speed that high when in gear will only increase fuel consumption when stopped at a set of lights.
« Last Edit: Apr 4, 2013, 10:50AM by SSS »