More Carb help......

[J8TRO]

Right after installing my AEM AFR and taking a quick drive Saturday afternoon i'm in the following position and i'm after a bit of advise on what to do next as i've searched and read a lot of great info on this site but some of it is conflicting and if someone can advise their preference i'd grateful.

Car is currently running at 18psi with a T28. As far as i'm aware the carb was standard when rolling road set up last year. The advise from the garage was they had changed the Main jet from 1.25 to 1.37 so it would fuel correctly.

However reading this thread:

https://www.rtoc.org/boards/showthread.php?t=460

I don't know if they are mistaking the Main Jet with A/C as the standard A/C is 1.25 and the main only 1.2

Anyhow, on idle the car builds within seconds to over 18 and i get --- on the gauge so its lean. On boost in 1st, 2nd and part of 3rd it's rich, running as low a 10.9. On a long drag in third gear above 3000k it goes over 17 running lean.

As yet i haven't ran it on WOT in 4th, but can tomorrow night and report back if this helps.

last year i changed the fuel filter but not pump. What would you carb hero's advise to do?

From reading the thread noted above, i'm tempted to return the main jet to its original 1.2 then reduce the a/c to 1.0mm and enlarge the 2nd stage to 1.2 or more................what do you think?

[GTphil]

If that 17 in third is at WOT I wouldn't bother testing it in fourth, from what you have said in your post you seem to be on the correct track every engine is differant in so many ways so all you can do is suck it and see and keep fiddling, just make sure you open the second stage up gradually

[GTphil]

That idle is super lean also, if the mixture screw isn't snapped or missing and doesn't have any effect on the idle mixture. (13.5/14.5 AFR is about correct)

have you got an air leak somewhere? Split vac pipe or carb base gasket? Definatly worth a closer look.

[Fordy]

I think a blocked idle jet could probably cause it to run lean on idle aswell

also check the acceleration pump jet and the pjmp adjustment aswell
then measure all your jets whilst its off and post back on here

[Brigsy]

Id start with 120 main jet, 100 a/c, 1.2mm 2nd stage. Might want a 2mm needle aswell.

Where have you fitted your lambda sensor? make sure there is no leaks in the exhaust giving u duff readings.

If you think the pump is playing up check the fuel pressure when on boost, connect a gauge up to test it. The fuel pressure should be 4psi above carb top boost pressure at all times.

[J8TRO]

We'll its all gone Pete Tong, tonight took the car out to double check my theory on performance. Its not running right at all, after warming up i ran conservatively down the local bypass, it stutterd and leaned off in 2nd, also 3rd and 4th, it was basically ****!

Anyhow, pulled on the garage down the road and checked all pipes for splits etc and any obvious problems, took the following video to show the readings i'm getting at idle and blipping the throttle.



Then went home, 1/4 mile max and with the temp at only half way the bloody red warning light came on (which i've never seen before) and got me worried the gauge was faulty! Pulled it on the drive the light went off and i checked water pressure everything and all seamed fine, i can only put it down to a gremlin!

See this...........WTF



Anyhow, the only thing i want to sort before having a mess with the carb is a strong smell of petrol in the engine bay. The fuel line to the carb is fine with no splits, where else should i check for fuel leaks as this would explain lean running?

Brigsy, the sensor is in the top of the exhaust just after the down pipe underneath the gear selector rod. I'd have liked it in the DP but it was going to be a mission at the weekend to sort, i did however check the exhaust and have no leaks.

At this rate with me away this weekend, looks like ill be in the 172 at Mallory

[Nayls]

There must be a leak or something somewhere as it would'nt idle like it does if it really was that lean!

Have you checked your breather system restrictor?

[Brigsy]

Ideally you need the boss in the downpipe mate, 6" or so away from the turbo.

Dont worry about the temp warning light, its either wiring fault or sensor is playing up in the water pump.

[J8TRO]

Nope, how do I.........i.e. where would i find it?

[J8TRO]

how do people check AFR's on a rolling road then or using a sniffer clamp. It's only another 6" to 8" away. Can it really make that much difference?

[Fordy]

as long as the sensor isnt to close to the back box its fine, even then it'll only cause reading issues at low rpms

check for an exhaust leak between the turbo and sensor

[J8TRO]

I'm quite confident i dont have a leak in the exhaust. Can anyone recommend places to check for fuel leaks, i cant see one on the line into the top of the carb but there is a strong smell of petrol.

Would it leak from the carb? where abouts?

[Sparkie]

I'm quite confident i dont have a leak in the exhaust. Can anyone recommend places to check for fuel leaks, i cant see one on the line into the top of the carb but there is a strong smell of petrol.

Would it leak from the carb? where abouts?

jack the car up.
follow the metal fuel hoses to the front of the car.
then carefully look where the rubber hose that joins the pressure reg and the metal fuel hoses are. - a pig to get to and they love to leak

[philg]

Mate im feeling your pain, as soon as mine is fitted i guarantee the fueling is going to be out.

I think my gearbox is fubar now, it only got rebuilt 700 miles ago .

Someone is going to buy a bargain gt this year if it does no buck its ideas up, i promise.


Good luck with it

[GTphil]

The strong smell of fuel coupled with the hesitation/stuttering would definatly suggest a fuel leak somewhere, as sparkie says follow the fuel lines from the carb to the regulator.

Also doesn't the AEM wideband also have a lamba setting? Might be worth checking you have it on the correct reading/display, as like has been said above that lean as it said on the guage and it wouldn't idle well if at all.

[J8TRO]

Also doesn't the AEM wideband also have a lamba setting? Might be worth checking you have it on the correct reading/display

I'll kick myself if its that, but will look as soon as im home tonight.

Sparkie, i'll also check all fuel lines as suggested. Thanks

[Brigsy]

how do people check AFR's on a rolling road then or using a sniffer clamp. It's only another 6" to 8" away. Can it really make that much difference?

From my experience you get a more accurate reading closer to the turbo matey, more accurate on part throttle/spoolup etc. When im using my sniffer clamp i only get half decent readings at WOT. Half hours job to whip the downpipe off get it done

Fuel smell could be the enrichment or acc pump diaphragm leaking, carb base gaskets leaking slightly have a good check round. Its not unusual for a gtt to smell of fuel though with nowt wrong

[J8TRO]

I haven't checked for the fuel leak tonight as the car got pulled out the garage and we've been working on a friends bike. I did however try to adjust my mixture screw and the little bugger is FUBARed and wont turn.

I have a rebuild kit to hand (thanks Smokey, who knew i'd buy it back). ill start ASAP.

i love these cars

[J8TRO]

Just incase any of you are messing with carbs over and above the overhall kit, this is the latest:

7701034196 - Mixture screw - AVAILABLE
7701033843 - Bung for mixture screw tube - AVAILABLE
7701017580 - Needle valve – AVAILABLE IN FRANCE (5-7 DAYS)
7701033690 - Idle jet (0.45mm) - AVAILABLE
7701029724 - Accelerator pump inlet non return ball valve – AVAILABLE IN FRANCE (5-7 DAYS)
7701032152 - Accelerator Jet – NO LONGER AVAILABLE

0853996428 - Main jet (1.20mm) – NO LONGER AVAILABLE
7703065152 - O ring seal for carb to top plastic (or alloy) elbow - AVAILABLE

7701026392 - 1.35mm main jet, seems this number now leads to air/enrichment jets. – NO LONGER AVAILABLE

These numbers no longer refer to air/enrichment jets. It seems they have been re-allocated by renault to the following parts.
6001007416 - 7mm oil breather pipe restrictor- AVAILABLE
6001007478 - 1.7mm oil breather pipe restrictor– ONLY 1 AVAILABLE

Can anyone please tell me where i can source any of thee jets? I've PM'd Stu on here but have had no reply, i know he had a load made up a few years ago.

[JRP]

southern carbs might help

[Jonny5]

They helped me out but they can only do main jets. They do all different sizes tho, call them on
01293 533843

[steer from the rear]

last time i had my jets set up on a rolling road years ago the dude solderd my jets and drilled them out???????

[phase i 16 v turbo]

Keep loads in stock.

[J8TRO]

Mike i'll call you later then to get some sorted.

I took the carb off last night and took it to piece's. It would seam the Jet's are all standard and Low Tech lied to me when they said they had changed the main jet!

Anyhow, i think the problem might be simpler than expected. The 2 water pipes which cross infront of the carb, behind the head are very dirty (see photo). Also the two nuts which hold the carb to the inlet manifold didnt seam the tightest. I think therefore petrol has been leaking from this point. It would explain the petrol smell, visual clues and running issues.....

Anyhow, ordered bits from renault, sorted a rebuild kit and i'm going to go to town on the carb this weekend anyway.

Do people agree that a leak at this point would cause the issues i've had?

[J8TRO]

Right, carbs been stripped cleaned and majority re-built. I have the items in the photo left over, now it does say in the rebuild kit that there are bits left over, i just want to check i dont have too many and have missed something important.

Where do the 2 green shaft seal thingys go?

Also the triangular item looks important but i cant find anywhere it would go???

Trying me best but the intructions with the kit are quite poor, and the guide on here is currently not showing any images. Any guidence would be welcomed.

[djinuk]

the two geen seals go on the throttle spindle matey.. the small red one i think goes..


** when you remove the top of the carb top theres that jet with a spring on the top, lift that out and where it seats there should be a fibre washer, i think that replaces that one**

the rest of the bits look normal

[J8TRO]

Anyone near to me got a carb base i can have / purchase? mine is fubar as the mixture screw is fcuked! i can come and pick it up anytime but want to work on the car tomorrow.

[phase i 16 v turbo]

Got loads but not local.

[J8TRO]

We'll carbs back on and the car ran on the first turn of the key. local lad LampsR5 gave me a carb base in exchange for some black gaffa tape! WIN

I've fitted a 1.0 a/c and a 1.25 main jet (thanks stu). i ran it for 1 min in the garage as it was just before 11pm and didnt want to piss off the neighbours. Its now sitting in the rich with AFR's of around 11 but i'm jet to mess with the idle, mixture etc.

Ill check it out tomorrow but feeling much better. been a stressful week with ND round the corner!

[J8TRO]

Been a right day of ups and downs, firstly messed with the carb this morning and got it ticking over sweetly, the mixture screw certainly helps!




Then got a call from Morg, he only really uses his 5 twice a year for Pod and Mallory poor bloke and long story short it's mixing water into the oil. so spent an hour taking the head off only to not really find anything, head seams fine, no cracks. The gasket shows no signs damage, we're a bit stumped but going to get a gasket tomorrow and put it back together and hope for the best.

before taking it apart the water was pressurising in seconds and with the cap loosely on the header tank it was pissing everywhere. You can see oil in the water and there is mayo on the underside of the rocker.






I came home and my car is only boosting at 15psi, so i've wound the actuator out but its made no difference. i had a bleed valve in the garage so chucked that on and now its only making 14psi no matter how much i unwind the screw?

Anyhow, i've pulled on the drive and the turbo's now smoking so i'm gonna get in the shower and go and have a drink.................looks like i'll be back to T2 power for Mallory.

On the up side if we don't fix Morg's car he'll be driving my 172 next week so i can find out how that compares on track.

another day in the life of 5 ownership i guess!

[Brigsy]

Wind the actuator in for more boost mate not out make sure theres no boost leaks.

[J8TRO]

Sorry Brigsy, i'm meant wind it in. Its now shorter, however boost just keeps dropping. It was 18psi last year, from running it this year noticed it was 16 a couple of weeks ago and now 15 and dropping to 14. With the smoke i'm guessing its giving up

[J8TRO]

Just a quick question, is the idle jet meant to be screwed in tight, or screwed in and then tweaked for adjustment?

[REBEL GT TURBO]

Just a quick question, is the idle jet meant to be screwed in tight, or screwed in and then tweaked for adjustment?

screwed in and then tweaked for adjustment

[J8TRO]

I've just had the best drive of my car in ages............i'm still grinning!

I re-read Brigsy's advise above (thanks mate) and checked all pipes etc, the only thing i'd done recently was add back in a dump valve, god knows why, i was trying to eliminate problems and thought i'd try it. anyway wipped it off, took the car out and it's boosting 18-19psi and the fueling is spot on. Downside, the turbo is definitely smoking.

So my answer.............if its on its way out! take the turbo out in style!

I went for a good blast, it was brilliant. I headed back home when i pulled up at one set of lights and got funny looks off people because of the amount of smoke chugging out the exhaust! Anyway, pulled on the drive, threw it in the garage and watched the blue cloud slowly drift across my neighbours garden! looked like something out a horror film LOL.

Car's now cooling down and ill whip the turbo off in the morning, i have a T2 i can use or ill try see what else i can get my hands on between now and Friday!

I love these car's...........

[Nayls]

Just a quick question, is the idle jet meant to be screwed in tight, or screwed in and then tweaked for adjustment?

screwed in tight!

[Brigsy]

Sounds like your getting there mate No smoke no poke

[J8TRO]

screwed in and then tweaked for adjustment

screwed in tight!

Can i have a 3rd and final deciding vote please?

[TrixNFlix]

Screwed in tight. I think rebel is getting mixed up with the mixture screw.

[Miller]

The idle jet holder in the body should be tight, and the mixture scre in the base should be adjusted to give 14.0ish afr I find if you go any leaner at idle it pops and bangs on overrun.

I normally screw the mixture screw in to it JUST stops then back it out three turns to get you in the ball park.

Chris

[J8TRO]

Thanks for the advise, ill go and have a mess in a short while. I took off the T28 this morning, there is a fair bit of play in the shaft, so smoke issue found. It will be going off for a refurb shortly.

Chucked on the T2 and set it up for 14/15psi i'm getting a little bit of boost spike as the actuator is rubbish, but i must admit it does make me smile, different car on the T2 with very little lag.

Anyhow, i'll be at Mallory on the T2 so should be good fun, fueling is fine.

[J8TRO]

I've done a 180 on my above post, this car is pissing me off! I've screwed the idle jet in tight, now it hunting like a mo fo, running either really rich to the point it cuts out, or running very lean.

In an effort to get it running the way it was i've messed with the idle jet again but now with no joy. The car is now running, feels fine and with WOT on boost is fueling fine, but at idle the AFR is off the scale lean............. any suggestions?

spent about 2 hours tonight just messing with the mixture etc and now i'm pissed off. I planned on cleaning the car tonight and sorting some other little bits.

[J8TRO]

Oh, on a good note, we fixed Morg's car. Turns out it was the head gasket, when we checked to see if the fan was working it wasn't. Will explain why the garage who recently did his MOT said it popped a hose. they must have left it running and not kept an eye on it. How annoying!

[Brigsy]

Idle jet might need cleaning? Check the o-ring on the brass screw that fits into the carb body aswell. Any air leaks on the inlet manifold?

[J8TRO]

Idle jet might need cleaning? Check the o-ring on the brass screw that fits into the carb body aswell. Any air leaks on the inlet manifold?

I have 2 idle jets, both have been cleaned with carb cleaner and both have the same effect when fully tightened into the carb.

Are you referring to the o-ring on the screw to access the main jet, if so it's new and very tight.

I'll check inlet tomorrow but have checked the carb connection to the manifold and it's nice and tight.

Lean would suggest an air leak right?

[Sparkie]

what does it say stamped onto the side of the idle jets? 44 or 45?

44 is too small....

worst comes to worst, i'm home from 6.30pm friday. u could pop by...

[IANMM]

Oh, on a good note, we fixed Morg's car. Turns out it was the head gasket, when we checked to see if the fan was working it wasn't. Will explain why the garage who recently did his MOT said it popped a hose. they must have left it running and not kept an eye on it. How annoying!

told you it was the garage

and with the mixture screw i have always wound it all the way in and then i think its about 1 1/4 turns out

https://www.rtoc.org/boards/showthread.php?t=4734

and keep cleaning the carb its prob just poo in it check how its fuling with carb top off too

[IANMM]

I've just had the best drive of my car in ages............i'm still grinning!

I re-read Brigsy's advise above (thanks mate) and checked all pipes etc, the only thing i'd done recently was add back in a dump valve, god knows why, i was trying to eliminate problems and thought i'd try it. anyway wipped it off, took the car out and it's boosting 18-19psi and the fueling is spot on. Downside, the turbo is definitely smoking.

So my answer.............if its on its way out! take the turbo out in style!

I went for a good blast, it was brilliant. I headed back home when i pulled up at one set of lights and got funny looks off people because of the amount of smoke chugging out the exhaust! Anyway, pulled on the drive, threw it in the garage and watched the blue cloud slowly drift across my neighbours garden! looked like something out a horror film LOL.

Car's now cooling down and ill whip the turbo off in the morning, i have a T2 i can use or ill try see what else i can get my hands on between now and Friday!

I love these car's...........

did you check the breathers and the oil return at the bottom of the turbo?

had same thing happen to me turbo was fine and it was down to back pressure in sump not letting the oil drain through the turbo into sump so it backed up into the turbo.....just pulled my oil seperator pot off and it cleared up

[Sparkie]

i hope your idle jet has the rubbery black O ring on it. - if not PTFE tape on the thread will do.
i also hope that your mixture screw came with a black O ring halfway down it....

[djinuk]

gota be leaking air somewhere, either as above mixture screw, or failing that could it be leaking air around the carb base gasket ?, maybe worth some silicon treatment here. Would the old easy start test work here ?? (spray easy start around the areas to see if the revs pick up , this would indicate an air leak).