Rev 3 - Hesitation under WOT but 1/2 throttle is fine

Discussion and technical advice the SW20 MR2. 3S-GTE, 3S-GE, 3S-FE etc
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CalMac
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Rev 3 - Hesitation under WOT but 1/2 throttle is fine

Post by CalMac »

Self explanatory really!

Full throttle the car feels quite laggy and holds back - feels reluctant to rev to the red line, but if boosting at more like 3/4 throttle it seems to be ok and sails along quite happily.

Boost looks to be holding at 1.15 bar regardless - does that rule boost leak out? I recently had the clutch changed and it's felt a bit slouchy ever since so perhaps a vac line has been nicked or come off. Doesn't feel like clutch slip and it shouldn't be slipping on a CT20 anyway (Exedy Stage 1). I've done a few hundred miles since the clutch swap so that should rule out oil/grime on the faces and breaking the clutch in.

I changed the spark plugs earlier this year to NGK Iridium 7, will check the dizzy cap and rotor arm tomorrow if I get time. The leads look ok but I've got a spare set I can swap in to try. Would a bunged up fuel filter or dying fuel pump cause these symptoms? AFAIK they're both original.
CalMac
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Re: Rev 3 - Hesitation under WOT but 1/2 throttle is fine

Post by CalMac »

Also if there is a boost leak - is it just a case of physically searching for it and squirting carb cleaner all over the place to check for sudden changes in idle? :-k
bri0905
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Re: Rev 3 - Hesitation under WOT but 1/2 throttle is fine

Post by bri0905 »

My bet would be ignition components. Sounds very similar to an issue I had which was rectified with new rotor arm.
96 Rev 3 Turbo, Done!
thomp1983
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Re: Rev 3 - Hesitation under WOT but 1/2 throttle is fine

Post by thomp1983 »

It's alot easier to look for vacuum leaks with a blowtorch, turn the gas right up but don't light it and it will come out in a cloud, direct said cloud at different areas, the butane will cause the idle to bog down as opposed to rev up the way carb spray does. It's alot easier way than hoping you spray a liquid aerosol in the exact right area
CalMac
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Re: Rev 3 - Hesitation under WOT but 1/2 throttle is fine

Post by CalMac »

I don't have a blowtorch but I do have Oxy-Acetyline, will that have the same effect? Sounds like it has the potential to blow stuff up :lol:
2barGee
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Re: Rev 3 - Hesitation under WOT but 1/2 throttle is fine

Post by 2barGee »

Change ign stuff first and check the plugs see how they look.

If that doesn't sort it i'd do a compression test. When i cracked a ring land i found full boost came in at 5,500rpm compared to 4,000rpm
Ryan S
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Re: Rev 3 - Hesitation under WOT but 1/2 throttle is fine

Post by Ryan S »

Ignition mate, Rev3 can run no bother with a boost leak. A blessing and a curse IMO :thumleft:
thomp1983
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Re: Rev 3 - Hesitation under WOT but 1/2 throttle is fine

Post by thomp1983 »

No idea what effect acetylene would have on an engine
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