Post #1
Hi everyone, first post, hoping someone out there can help as im about to cry haha. Ive been running my 205 with gti6 conversion for about two weeks now, she's been fine really, replaced speed sensor on gearbox last week and she was cool again. This morning i went out and started her and off i went to work, couple minutes in to my journey.. missfires, wont run at all if i hold steady revs but if you floor it shes fine! Thought it could be o2 sensor so swapped it out for a used one i had (so there is no guarantee its good) However its made no difference and im starting to think its not o2 because it missfired badly from cold when started after i finshed work... as i say if you dump theottle its spot on so doubt its plugs or coils or fuel relay as its spot on, but try holding steady low revs and it sounds like its about to detonate all over my workshop!!! Any ideas anyone, sorry for the essay! Cheers guys
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displaying posts 1 to 25 of 33
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| Author | Subject: bad engine missfire at low revs |
 garwilk
Newbie  Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
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 Posted 30th Jan 2015 at 20:39
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pug_306
Seasoned Pro  Location: Great Hockham Registered: 28 May 2013 Posts: 1,597 Status: Offline |
Post #2
Could be fuel pump / injection relay, i had one with simular fault last week. Try a known good one.________________________________________ 1998 Supercharged White Rallye1992 205 GTi6 205 Turbo 340bhp |
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Posted 30th Jan 2015 at 20:50
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #3
Are they both same relay? As in twin one in engine bay next to ecu? Still baffles me how if you rev high its spot on, purely when you hold revs steady? |
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Posted 30th Jan 2015 at 20:53
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pug_306
Seasoned Pro Location: Great Hockham Registered: 28 May 2013 Posts: 1,597 Status: Offline |
Post #4
Yes thats the one, or could be a air leak but my money is on the relay or TPS but i would try a relay as sounds like exact syptomns i had on a gti6________________________________________ 1998 Supercharged White Rallye1992 205 GTi6 205 Turbo 340bhp |
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Posted 30th Jan 2015 at 21:14
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armzsc6
Seasoned Pro  Location: Crowborough Registered: 22 Mar 2008 Posts: 3,445 Status: Offline |
Post #5
You can rule a few sensors out on these engines as they run without them. Disconnect the lambda and go for a drive if no better reconnect and then removed the TPS or MAP or IAT sensor and do the same. If it runs better without one then it's up the swanny. Can be coils breaking down and they only provide a decent spark under full load but fairly rare. I'd also try the fuel pump / ignition relay behind the battery as it powers most of the engine. ________________________________________ Black power baby! SUUUUUPERCHARGED Seat Leon FR TDI 190BHP 300lbft daily gti-6 killer :p 12x 306's owned so far Cambelts, clutches, service work carried out on All makes and models, Peugeot Citroen / mitsubishi specialist. Pug planet / Citroen Lexia diagnostics / code reads available. |
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Posted 30th Jan 2015 at 21:13
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #6
Ive unplugged pretty much every sensor on the throttle body and inlet IAT, MAP,TPS etc even tried ecu temp on water jacket and obviously o2 but none have made any difference, it missfires and backfires and pops so badly in the workshop to do any type of road test id have to pretty much back out and drive off red lining it! Wont tickover and if i hold revs constant its more backfire than go! p**sing me off because rev her up and shes fine! You'd think fuel relay would be all or nothing and certainly not better under high demand!! Would i be able to jump a couple pins and bypass the relay to see if thats any better??? |
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Posted 30th Jan 2015 at 21:24
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welshpug!
Capt Pedantic  Location: Bigend, Wales. Registered: 27 Mar 2007 Posts: 25,871 Status: Offline |
Post #7
highly unlikely its the relay if it actually runs.________________________________________ need a part number? get on here - http://public.servicebox.peugeot.comBring on the Trumpets. |
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Posted 30th Jan 2015 at 21:37
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pug_306
Seasoned Pro Location: Great Hockham Registered: 28 May 2013 Posts: 1,597 Status: Offline |
Post #8
welshpug! wrote: highly unlikely its the relay if it actually runs. Had a couple with relay faults, where they over fuel and still run but badly. ________________________________________ 1998 Supercharged White Rallye1992 205 GTi6 205 Turbo 340bhp |
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Posted 30th Jan 2015 at 21:48
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #9
Can it be pinned to bypass it, im sure i read somewhere you can? And this is whats doing my head in, im pretty switched on so understand o2 sensor being open loop until temp rises and everything but just doesnt make sense it should be so lumpy under minimal revs yet goes like a train balls out! I had an rs turbo that did similar and it was always fuel relay, anyone who knew them always had a couple spares in they're glovebox  dont want to start buying sensors keft right and centre and ripping the car to bits unless i have to! |
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Posted 30th Jan 2015 at 21:56
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bigbadbowen
Seasoned Pro  Location: Winchester Registered: 21 Nov 2003 Posts: 13,753 Status: Offline |
Post #10
Why did you replace the speed sensor ? |
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Posted 30th Jan 2015 at 22:05
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bigbadbowen
Seasoned Pro Location: Winchester Registered: 21 Nov 2003 Posts: 13,753 Status: Offline |
Post #11
Are you using the original fuel pump as well ? I've had huge problems with fuel pumps on 205s |
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Posted 30th Jan 2015 at 22:07
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #12
Speed sensor/crank sensor (top of g.box, 10mm bolt) because it was playing up, cut out and would only start on tow, ohms reading was out on starter crank where as bumping was slow enough for sensor to pick up reading i guess! Ran fine once bumped but wouldnt go on starter crank for love or money, that was a week ago and had been fine until this morning! |
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Posted 30th Jan 2015 at 22:11
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #13
Umm, guessing its original fuel pump, i bought the 205 with conversion already done but... call it a barn find! So ripped the engine out and stripped and rebuilt it and put it all back together etc etc. Whoever paid to convert it originally spent alot of money on it, has all been done properly, only thing that doesnt work is rev counter, i have been told it needs a mod behind clocks for rev counter but would imagine its more getting a pin out for ecu and wiring it up?? |
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Posted 30th Jan 2015 at 22:21
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #14
Only other thing i can ad is that a couple times when i started the engine it almost wanted to rev flat out of its own accord, so had to kill it, am thinking may just be because id removed many sensor plugs and plugged back in without disconecting battery! |
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Posted 30th Jan 2015 at 22:27
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bigbadbowen
Seasoned Pro Location: Winchester Registered: 21 Nov 2003 Posts: 13,753 Status: Offline |
Post #15
check the fuel pump under back seats ? The rubber seal in the housing perishes and cause all sorts of problems ? If it's original to the car it will be pretty old ? Be warned Walbro pumps don't fit ! |
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Posted 30th Jan 2015 at 22:57
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #16
Ok thanks for your help, im going to concentrate on fuelling tomorrow ie relay as well because i think ignition would be more obvious! |
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Posted 30th Jan 2015 at 23:05
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bigbadbowen
Seasoned Pro Location: Winchester Registered: 21 Nov 2003 Posts: 13,753 Status: Offline |
Post #17
Start with the fuel pump bud ? Fuel lines could be leaking at the pump as well ? I had an issue with a fuel pump that caused my 205 not start for ages and then cut out / run Badly randomly I swapped the whole thing for a good working one and sorted the problem. Closer inspection on the fuel pump I found a split in the rubber joining pipe inside the housing |
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Posted 30th Jan 2015 at 23:13
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #18
Well ive cleaned every inlet sensor today, swapped fuel relay and believe the pump 8s working how it should do, the revs are so randon i think its either a sensor or ecu fault... will have to try and plug a computer in to the data link cable! |
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Posted 31st Jan 2015 at 16:31
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welshpug!
Capt Pedantic Location: Bigend, Wales. Registered: 27 Mar 2007 Posts: 25,871 Status: Offline |
Post #19
check for air leaks, especially the resonator under the inlet, and the inlet itself.try a replacement idle valve, unplugging s**t rarely helps. ________________________________________ need a part number? get on here - http://public.servicebox.peugeot.comBring on the Trumpets. |
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Posted 31st Jan 2015 at 17:34
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bigbadbowen
Seasoned Pro Location: Winchester Registered: 21 Nov 2003 Posts: 13,753 Status: Offline |
Post #20
Did you take the fuel pump out and actually check it ? |
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Posted 31st Jan 2015 at 17:45
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #21
No i didn't, does seem to be primimg up ok and seems to be delivering enough fuel at high revs? Do they not pump a constant 1.5bar or something similar? I suppose i can give it a go?... |
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Posted 31st Jan 2015 at 20:13
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #22
There's no resonator on there, been blanked off, and no it wont be down to that, people think it gives a cleaner rev curve without resonator but it actually makes hardly any difference at all! I will have to swap out sensors but its an expensive old game!! |
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Posted 31st Jan 2015 at 20:16
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welshpug!
Capt Pedantic Location: Bigend, Wales. Registered: 27 Mar 2007 Posts: 25,871 Status: Offline |
Post #23
fuel pressure is 3 bar.________________________________________ need a part number? get on here - http://public.servicebox.peugeot.comBring on the Trumpets. |
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Posted 31st Jan 2015 at 20:20
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garwilk
Newbie Location: Tavistock Registered: 24 Jan 2015 Posts: 17 Status: Offline |
Post #24
Does fuel pressure change or is it constant 3bar from idle to full throttle? |
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Posted 1st Feb 2015 at 08:55
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bigbadbowen
Seasoned Pro Location: Winchester Registered: 21 Nov 2003 Posts: 13,753 Status: Offline |
Post #25
Regulator on fuel rail is 3bar so it can't be any higher. - just take the fuel pump out and give it the once over- it's only held in with a few bolts under the back seat - they do fail after all it's 25 years old |
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Posted 1st Feb 2015 at 09:14
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