more starting issues! - throttle sensor?

[mike1978]

hi,

i`ve finally got my engine in and water leak free - i`ve also made an exhaust for it to.

the problem i have got is with starting - it used to start then idle with a bit of a rough idle - i.e it was low rpm, then high rpm, then would stutter to cut out. it also when you came to rev it, would have a flat spot when you blipped the throttle and sound like it would backfire, but if you moved the throttle slowly, you could raise the rpm.

anyway, i removed the idle air control valve and checked that was clean - sprayed some carb cleaner in there just in case. i also removed the throttle control sensor and cleaned that too - i replaced it as close to where it came off - i can just see the screw marks and lined it up to where i think it should be.

i now can`t start the engine - sometimes it just catches on the first turn of the key, then keeps on cranking over without starting.

i`m getting an error code 31 which indicates the throttle sensor but i`ve moved it in smal increments right across the range and no difference at all.

i`ve checked the throttle butterfly and it looks about right - easy to move but looking pretty much closed. the cold start wiring is in place and connected to the starter solenoid.

i`ve just removed the plugs and they were a bit damp with petrol as i may have flooded it - can you flood a fuel injection engine!?

is there any guide to setting the throttle sensor up? could it be something else?

if it was an lawn mower motor, i`d straightaway say there wa dirt in the carb or the timing/fuel mixture was out.

is there a procedure for setting these motors up from scratch?

thanks, mike

[rjes]

We already discussed this for an hour on the phone, but in case anyone else is reading, the cold start wire is connected, and Mike did get a TPS error code after re-installing the throttle position sensor. A fuel injected engin would bu much easier to flood of it's throttle position sensor is set way out.

Suspect the idle speed control valve is sticking or otherwise not working, causing the initial unstable idle, and the reluctance to start is probably due to flooding (as the exhaust smelled of petrol).
_________________
Regards,

Richard,

R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com

[mike1978]

thanks richard - i also forgot to add for anyone else reading that the throttle senor has 3 wires going into it on mine - a black, a white and a red and black wire.

its a 98 impreza sport engine.

i`m going to go and see if it`ll start now after letting the fuel evaporate (hopefully!)

[mike1978]

i just went out and to try again - i replaced the dry plugs after leaving it for a good half hour.

i also removed the throttle sensor again to check it was dry inside and replaced it using the marks left by the screws.

i then reconnected the battery - when i turned the ignition on, the error code 31 has gone - when i crank the engine over though, it still doesn`t start.

interestingly, this time if i blip the throttle just i start to turn it over, the engine catches, then just cranks over as before - it does this every time now, not just on the first try.

i`ve come in now as its chucking it down and getting dark quickly. i`ll try starting it again tomorrow before i go to work just to make sure that its not flooding causing the problem.

[mike1978]

i tried starting this morning and i still have the same results. The only things i have messed with/changed since the problems started are the idle air control valve - i took the top off and cleaned it with carb cleaner, the throttle position sensor - removed, cleaned with carb cleaner, then refitted in approx same position and finally i fitted the exhaust system.

the only thing i can think of now is that because the engine is difficult to start, perhaps the exhaust system is too restrictive - tonight, i`ll remove the exhaust to eliminate it i think.

[richbaker78]

[mike1978]

yep - it started on the button before i fitted the exhaust. i`m hoping that this is the problem !!!

[mike1978]

i managed to sort the problem, more by luck than anything!

at the moment, the rear of the van is up on ramps. i jacked the front up to adjust te throttle cable. while it was up in the air, i thought i`d give it a go at starting and it started and idled!

dropped it back down and it wouldn`t start. Turned out, that i`ve got that little fuel in there that it would have enought to pump a bit through when initially cranked over, hence the initial fire of the engine, but then air after that so that it`d just crnk over!

bit of a schoolboy error, but i`m just glad it was something simple!

[richbaker78]

LOL
glad you got it sorted - nice cheap and easy fix then!!!

[ElusiveStranger]

My sides really hurt

Rich, cheap fix??? I can tell you haven't bought fuel for a while
_________________
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'78 Bay, 2 litre 091 box, EJ20 NA & the ashtray's on the 'right' side.
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Bugger, missed out on "Live fast, die young"

[mike1978]

the only reason i`m changing my old diesel to this subaru is to get the cheaper unleaded petrol