No Engine Braking

[24seven 104]

This is really bizarre, I'm getting virtually no engine braking from my GTi6 engine. If I push the clutch pedal while the car is rolling, it will hold at the same RPM it was at and won't drop down to idle until the car is stopped. It's also started being really temperamental at part throttle, especially while pulling away from junctions. It feels like it's not getting any fuel through, though the pump I know is fine and there are no blockages in the lines or filter. My guess is a sensor issue, or combination of sensors failing. Any thoughts?

Edited July 25, 2011 by 24seven

[dcc 855]

air leak, id personally take off the inlet and check over the resonator box for cracks or holes.

 

also make sure all sensors are plugged in

[24seven 104]

Yup, they're all plugged in. It wasn't like this when the conversion was first completed, whilst the engine was in the xsara it was a little slower returning to idle than I thought it should be but that was as bad as it got, no stalling etc. Forgot to add the part-throttle stalling at junctions isn't quite as bad once the engine is up to temperature, but it's still a major problem and makes the car near undriveable in traffic.

[dcc 855]

well I'd first check for an air leak, as well as making sure the throttle body is fully closed when it should be.

[CosKev 16]

Have you got a speed sensor fitted?

[24seven 104]

Yeah, it's still using the ECU only sensor until I get a duel output type. I don't think it's got any air leaks, it had a new inlet manifold gasket during the swap and when idling blocking the ICV feed cuts the engine out pretty sharpish. Went out and tried a few scenarios on it see what makes it happen and I'm pretty sure it's ICV/MAP related. Pulling away from a standstill if I use the clutch only and no throttle it pulls away smoothly and holds idle rpm well. As soon as I touch the throttle it tries to cut out.

[kyepan 291]

do you still have the odb diag port (or pug equivilent) as you may be able to get some fault codes out to diagnose the fault, failing that back probing some of the sensors relating to map and throttle may help, if they are out of range or not returning to their static values in the way they should.. you may be able to narrow it down.

 

some people also use cold start to diagnose faults and leaks in the inlet.

[Paul_13 212 1 Cars]

Sounds like icv, was having similar problems

[Toddy 7]

Air leak on the inlet side, replace the gaskets and seal the resonator, you can't get air down a wire!

[Paul_13 212 1 Cars]

The icv may not have been opening and closing as it should. Thats why I said it.

Mine would stay shut and stall or open wide and revs would go to 3k and would only settle when back to stationary.

[24seven 104]

Haven't still got he diag port as the engine came from a P2 Xsara and the loom was pre-converted by Spiky. After tinkering alst night I left it until today with the battery disconnected and it's stopped stalling when pulling away from junctions, but still doesn't like idling until stationary. I'm picking up a new thermostat housing from a 306 variant of this engine as the P2 Xsara doesn't have an outlet for the dash coolant temp sensor in the right thread, and I'm also picking up a replacement MAP sensor, so I'll take the ICV off and make sure it's clean and free while I do the other jobs.

 

How would I go about testing the TPS for faults?

Edited July 26, 2011 by 24seven

[dcc 855]

think about this logically.

 

your engine is holding revs

 

so to do this, it would need more air. for it to physically get more air, there must be a gap/leak somewhere along the line. I think its a leak after the throttle body, as it isnt being metered by the ecu.

 

because it is having more air than it thinks, its holding the revs, and because the TDC is recognising the engine revolution speed, the ecu is feeding it fuel.

 

Does the car feel slightly gutless/under powered? I think it might be.

[24seven 104]

[epic bump]

 

Definitely not gutless or underpowered. My arse-dyno says it's no slower in a straight line than my 205 Mi16 was, despite the extra weight and slightly longer gears. Since the last update I've changed the TPS and replaced all gaskets and seals on the inlet side to ensure there are no leaks. Indeed, partly covering the ICV hose with my thumb while the car is idling will choke it and it cuts out. However, the engine braking issue has changed and gotten worse...

 

Cruising downhill, 60mph and above, off the throttle completely, the damm thing starts kangarooing! It's really bizarre, the faster I'm going the worse it gets. If I take it out of gear or depress the clutch it still maintains roughly the same RPM as it was doing whilst in gear/clutch engaged. It's also become extremely gutless from a standstill. As soon as the car is moving, it finds it's arse and has a bit of power again but pulling away from traffic lights it needs a lot of RPM to stop it from stalling, which isn't doing the clutch any favours!

[dcc 855]

is your cable releasing properly?

[Paul_13 212 1 Cars]

Throttle body gasket ?

[24seven 104]

Throttle body was off and cleaned and working/seating properly with a new gasket. As soon as the car comes to a standstill, it idles perfectly at around 1000rpm, so I don't think it's got a leak.

[Paul_13 212 1 Cars]

Try a new MAF sensor and icv and go from there. Sounds as though the icv is closing/opening on its own accord. Or MAF is dodgy throwing the readings out

[harryskid 193]

Mine was like that when the motor was first fitted and let me down on two rallys. This was with the standard tb and got so bad it would not run well and backfiring with flames out of the exchaust. After a leak down test it was found to have blown the tb. My answer was to ditch the great big piece of crap and had proper tbs and an emerald ecu. Got loads more gee gees too.

[24seven 104]

After replacing more sensors (new MAP sensor cured the kangarooing off-throttle) and knowing for 100% certain that there are no gasket leaks on the inlet, I've been gong mental trying to figure this out... Until the last time I sat in the car. I got in after a short drive and pressed the brake pedal before starting the engine only to find it was rock hard. The Brake servo has a vacuum leak, feeding air into the inlet manifold... the car is off the road ATM as the tax and MOT have run out, but next chance I get I'll take it for a short spin with the vacuum hose disconnected at the servo and blocked off, see if that makes it behave.

 

In the mean time I'll save starting a new thread and ask here; is the 309 GTi master cylinder & Servo the same as the 205 1.9 GTi? Also is this the correct dual output speed sensor for a GTi6 conversion? It looks about right, but just want to double check as i'm a student and can't afford £20 on the wrong part.

Edited January 7, 2012 by 24seven

[24seven 104]

[edit] Double post

Edited January 7, 2012 by 24seven

[Paul_13 212 1 Cars]

The tee piece that sits just above vacuum pump is a one way valve, make sure its right way round

[welshpug 1,657]

sensor looks right, pretty cheap, I'd ask what brand it is.

 

these are sagem items from a known seller http://www.ebay.co.uk/itm/PEUGEOT-406-306-93-SPEED-SENSOR-RPM-GAUGE-616024-/220878490174?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item336d624a3e

 

same price give or take a few pence.

[24seven 104]

Cheers WP. I'll have one of those then.

 

Paul, the T piece is the right way round, the servo itself has been damaged. Presumably through contact between the end of the MC and rocker cover, as although I've spaced the pedals out to clear it the engine mounts are a little past their best and it does contact now and then. </div>