High speed engine misfire

High speed engine misfire

Author
Discussion

Richard7K

Original Poster:

55 posts

160 months

Sunday 29th June 2014
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Hi Guys,

My SR3 ran like clockwork for the first 78 minutes of our first three hour enduro, but 12 laps after we re-fueled and changed driver the engine started with misfire which wouldn't let us go past 6500rpm. Going foot flat would cause it too.

We've replaced the coil, plugs and leads, and now moving on to the fuel side, checking the fuel filter, pump and injectors.

Has anyone else battled a similar misfire with their car and have some wisdom to share please?

It's a 2003 SR3 with a Gen 1 1300 in stock RPE config.

Thanks
Rich

Simon T

2,136 posts

273 months

Sunday 29th June 2014
quotequote all
Can you pull the data from the ECU?

Elton

2 posts

117 months

Tuesday 8th July 2014
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Not able to get any data as it's a locked Radical unit.

Have gone and changed the following parts and now getting to the end of our tether:
plugs, coil, leads, O2 sensor, fuel pump, TPS, cleaned the chassis earth point.

Injectors are getting tested tomorrow.

Basically feels like a hard cut that comes in at around 6500rpm.

jpivey

572 posts

218 months

Tuesday 8th July 2014
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I had the same issue with an SR3 I had for a while changed everything, turned out to be the engine loom that was the problem.

Simon T

2,136 posts

273 months

Tuesday 8th July 2014
quotequote all
You should still be able to upload the data, just not make any changes

Simon

bloberoo

92 posts

159 months

Wednesday 9th July 2014
quotequote all
Battery voltage/ charging circuit ok??? ... rectifier??
load misfire?.
Long shot but also Ambient air sensor on bulkhead???
.... unplug it and see if symptoms alter...worth a try..

bloberoo

92 posts

159 months

Wednesday 9th July 2014
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ambient/ or atmospheric sensor ?.... ( it was a while ago) basically black/ plastic/ rectangular:-)

With these feet

5,728 posts

215 months

Wednesday 9th July 2014
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Can you swap out the ecu for another? Not the same issue but had a coil driver fail, that was a constant miss-fire.

LCM

444 posts

197 months

Wednesday 9th July 2014
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Simon T said:
You should still be able to upload the data, just not make any changes

Simon
I agree!

I've got a locked LIFE on one of my cars and can download all the data from the LIFE (and from the AIM). I just can't make any changes to the parameters in the LIFE.

If you're stuck, why not apeak to Andrew at RPE?

Elton

2 posts

117 months

Thursday 10th July 2014
quotequote all
Hi guys,

Quick update:
- we did a test run and unplugged the barometric which kind of helped (st low end but let use rev out at the top end good)
- strapped the jump battery in and found that it cleared the issue for a few laps
- got the charging circuit tested and looks like we have found a fault rectifier(?) so are getting a new one in along with a new barometric to be safe and will run it again early next week.

Our ECU is an old MBE one and doesn't have any ability to access any data (spoken to MBE to make sure).

Will keep you updated once we run it next week.

If it continues then we'll work on JPI's suggestion of pulling the loom out and checking that.

splitpin

2,740 posts

198 months

Thursday 10th July 2014
quotequote all
Elton said:
Hi guys,

Quick update:
- we did a test run and unplugged the barometric which kind of helped (st low end but let use rev out at the top end good)
- strapped the jump battery in and found that it cleared the issue for a few laps
- got the charging circuit tested and looks like we have found a fault rectifier(?) so are getting a new one in along with a new barometric to be safe and will run it again early next week.

Our ECU is an old MBE one and doesn't have any ability to access any data (spoken to MBE to make sure).

Will keep you updated once we run it next week.

If it continues then we'll work on JPI's suggestion of pulling the loom out and checking that.
Looks like Bloberoo is the comfortable winner of the 'Dead Eye Dick' Award then biggrin

If you do have to progress further with the loom checking, suggest you start with the LT side, particularly the spade connectors as I assume you will have them on the coils of this earlier SR3?

AJWSNR

70 posts

122 months

Thursday 10th July 2014
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Had similar problem on pr6 engine , the coil has 3 wires and In my case one had broken. Relays are a problem as well. Lay a bet coil pack wiring issue

AJWSNR

70 posts

122 months

Thursday 10th July 2014
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Had similar problem on pr6 engine , the coil has 3 wires and In my case one had broken. Relays are a problem as well. Lay a bet coil pack wiring issue

minitici

200 posts

205 months

Friday 11th July 2014
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AJWSNR said:
Had similar problem on pr6 engine , the coil has 3 wires and In my case one had broken. Relays are a problem as well. Lay a bet coil pack wiring issue
Yes relays and relay bases can be a problem with MBE looms.
Had a similar problem with a Westfield Megabuse - replaced the main power relay and tightened the connectors in the bases and the stuttering went away.

ric355

215 posts

149 months

Friday 11th July 2014
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I've just replaced the 75A relay on my car due to the previous one failing. Charging system stopped working again (it's in the line from the battery to the regulator output). When I opened it up the old one was badly corroded. The reason I mention it is the engine misfired until this relay was replaced due to low voltage reaching the coils.

Note the rectifier will appear to be faulty if this relay isn't working because it is inline between the rectifier and the battery.

Edited by ric355 on Friday 11th July 18:43