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Hi folks,

 

Over the winter I thought I'd do a bit of tuning to my 1600 Zetec se... 

 

I've gone from a standard engine running Omex 600 on standard induction to the same engine with Shawspeed ss4 (fast road) cams, high tensile rod bolts and GSXR1300 throttle bodies and injectors.

 

Now then I've managed to set the TPS for the new throttle bodies via the Map3000 software and Omex sent me a more suitable start up map but it is still not idling. I can start the engine by depressing the throttle pedal slightly, it will run but it isn't very smooth and when I let go the rpm drops to around 600 and then stalls.

 

Can anyone give me some pointers as to how to get the engine to idle and run a bit smoother? I will be taking it to a suitable tuner for fine tuning but I would prefer to get it a bit smoother before I take it.

 

cheers

 

Stevo 

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Welly Jen

Have you had a chance to balance the throttle bodies? If it starts and sort of runs, then that should be your first step I think. Certainly helped when I started my car for the first time. I set it up initially with the same very small opening when the throttle was closed, identical by eye on all four throttles. Once the engine was running I could tthen use a vacuum gauge to balance between them. You can get synchronometer air flow meters, or some people use a tube to listen for the hiss and use that to balance them. If the throttles aren't balanced, you won't get a smooth idle.

 

If the engine drops to 600 rpm it is near to stalling anyway. A bit more fuel in the very lowest RPM bin of the map can add a bit of a kick to the engine to get the revs up again. I found.

 

Needing a bit of throttle could just be the throttle stop needs adjusting, or possibly that the mix is rich and needs extra throttle opening to lean it out? If you adjust the throttle stop, then the TPS will need calibrating again.

 

My car was very similar to yours when first started on throttle bodies. Balancing the throttles smoothed it out a lot, followed by some initial tuning with a wide band lamda sensor to get it in to a state that I could gently drive it to a proper tuner.

 

Jen

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Thanks for the replies.

 

I haven't balanced the throttle bodies and have a synchrometer but since it wont idle I cant really use it. I could adjust the throttle stop so that it idles and then balance the bodies and then wind the throttle stop back, however with the butterflies more open wont they be sucking too much air in to get them balanced? I did a bit of juggling last night with one hand on the the throttle peddle and one holding the synchrometer and it was reading really high with the throttle pressed but it wasn't a very scientific approach! 

 

The TPS is set by putting in min and max values and the ECU converts them to 0-100%

 

 

 

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blue ass fly

Are you 100% sure the cams are timed up ok

One tooth out will give your symptoms

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Are you 100% sure the cams are timed up ok

One tooth out will give your symptoms

 

I was confident... but I can check again :-)

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Welly Jen

Thanks for the replies.

 

I haven't balanced the throttle bodies and have a synchrometer but since it wont idle I cant really use it. I could adjust the throttle stop so that it idles and then balance the bodies and then wind the throttle stop back, however with the butterflies more open wont they be sucking too much air in to get them balanced? I did a bit of juggling last night with one hand on the the throttle peddle and one holding the synchrometer and it was reading really high with the throttle pressed but it wasn't a very scientific approach! 

 

The TPS is set by putting in min and max values and the ECU converts them to 0-100%

That would be the way I'd approach it. Adjust the throttle closed stop to get it to idle faster, balance the throttles with the synchronometer, then adjust the throttle stop back again till it hopefully idles at a suitable speed, then reprogram the TPS setting. A fast idle will give more air going in, so a higher reading on the synchronometer and hopefully easier to get the same reading on each intake.

 

I'd want a fairly fast idle, 1000, to 1200rpm at this stage when you are just getting it running. Less chance of stalling when warming up and you haven't got the warm up maps set up properly.

 

Jen

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Can you balance the throttles by using either feeler gauges or a small drill shank between the butterfly and body, to get somewhere near before using your synchronometer?

 

 

 

..or swap it all out for a Pinto on carbs. :p

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blue ass fly

Mig wire under the butterfly is good for rough balancing - or an old guitar string

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