268 cams installed and higher fuel consumption?

[dukest 0]

After a mammoth weekend of work by Toad and Peanut on my car I finally got home at 2.30 on Sunday morning with a new clutch, new chains/tensioner, new head, new cams, BMC filter, new water pump, thermostat housing etc etc etc. Very, very grateful to them and to Nikki for a great bbq and being so patient while her weekend was monopolised!

 

The car feels dramatically different (in a good way :grin: ) - really willing to rev and surge forward whenever I put my foot down now. The only slightly unexpected thing is about a 5mpg impact on fuel consumption if i drive it at all enthusiastically (above 2.5-3k).. Obviously it hasn't been remapped yet but when I spoke to Vince about this he said higher fuel consumption might be a slight timing issue. I know we checked this carefully but I just wondered if anyone else had any theories about whether that or anything else which might mean the car was a bit more thirsty?

 

Thanks for any ideas!

John

[mic_VR 3]

I think It'll be called heavy-right-foot-itis mate, now you're got all this power! :wink:

[mrbeige 0]

I think It'll be called heavy-right-foot-itis mate, now you're got all this power! :wink:

I might have to agree :lol: I said the same thing to Tom last night, when he said that your fuel consumption wasn't as good

[steve @ 0]

Cant say I noticed much of a difference in fuel consumption after fitting my 268's (not mapped yet either). Try running on 97/99 ron fuel and check tyre pressures did you reset the ecu after fitting? Vince also advised me not to take it above 5k too much in this weather with it not being mapped.

[ANTIHERO 0]

well they reckon the first 3 months after installing a mod can make it a bit more thirsty due to the driver putting his foot down more , once it wears off you should see normal MPG......

 

i had the same when i had my cams done....getting my charger next week fitted so its going to be even worse

[dukest 0]

lol, yeah i understand that its very tempting to use the additional power thats there but i have tried to drive it differently for a reasonable comparison

 

eg. Monday normal driving to work = low 20s mpg when normally it would be 27-28, Monday very careful driving home from work, low 30s mpg. so, being careful it gives the same results, driving normally it gave worse than normal results..

 

ECU reset would be an idea though i guess, can someone remind me how to do it? I did watch Vince once but didn't really pay enough attention..

[Toad 0]

If you can make it down on Sunday I'll chuck vag com on and see if there is anything funny with any sensors. Seems a bit odd to be that much lower on fuel economy.

[ANTIHERO 0]

have you reset the MPG on the stalk?i cleared mine the other day and got higher readings???

[JayGT 0]

Hello John,

 

I had the same problem. MPG was well down before I had my remap a Stealth. It did get better after Vince had a play but still isn't great. He did have to replace a dodgy HT lead which was causing a misfire and I do have a VSR + 6 branch manifold but I guess this is always gonna be a downside of squeezing more power out of the lump.

[mrbeige 0]

I know this could be a long shot, but are the temp sensor plugs on the right way round?

[The_Dude 0]

Wow, lots of stuff going on there mate, are you enjoying the BMC roar?

 

Must be a nice improvement on before.

 

Do you have a gallery?

[Kevin Bacon 5]

Buy a 1.0 Corsa if mpg is so important

[mic_VR 3]

Buy a 1.0 Corsa if mpg is so important

 

Say what you think Kev! :lol:

 

Having my 263 cams done this weekend, I'm sure the drive home won't be very fuel friendly...

[herisites 0]

Buy a 1.0 Corsa if mpg is so important

 

Say what you think Kev! :lol:

 

I think Kevs having a bad day :lol:

[Supercharged 2]

Buy a 1.0 Corsa if mpg is so important

 

LOL :)

[dukest 0]

Hello John,

I had the same problem. MPG was well down before I had my remap a Stealth. It did get better after Vince had a play but still isn't great. He did have to replace a dodgy HT lead which was causing a misfire and I do have a VSR + 6 branch manifold but I guess this is always gonna be a downside of squeezing more power out of the lump.

Cheers Jay, the remap is definitely needed as it theres definitely more power :grin: but not always evenly up the revs

 

I know this could be a long shot, but are the temp sensor plugs on the right way round?

pretty certain they are Stu but will check everything again! cheers for your helping hands on saturday too!

 

Wow, lots of stuff going on there mate, are you enjoying the BMC roar?

Must be a nice improvement on before.

Do you have a gallery?

No gallery yet Jim but have some shots from the weekend that will be used to get one going soon! It certainly is a roar, theres a point where the whole car resonates around 4k! :)

 

 

if mpg is so important

yeah, I dont remember complaining about the mpg - just asking if anyone could think of anything untoward with the engine that could be causing it to be lower? you know, seeing as a man that some people think knows what he's talking about said it shouldn't have changed.. :?

[mrbeige 0]

I know this could be a long shot, but are the temp sensor plugs on the right way round?

pretty certain they are Stu but will check everything again! cheers for your helping hands on saturday too!

No worries John, didn't do a great amount comparatively speaking, apart from showing my legs :lol:

[Leonard 0]

Must admit I have never really got the more power same fuel used argument, doesnt really compute :scratch:

[Kevin Bacon 5]

Maybe it's just me but the last thing I look at when modifying the engine is the MFA! I just get on with it and enjoy the car for what it is. If it's more thirsty as a result of engine mods, c'est la vie.

 

You must have been studying the MFA for ages to arrive at the precise 5mpg reduction, or calculated it at the pump. Which suggests to me your main priority is fuel economy, rather than performance - hence my facetious

remark about a 1.0 Corsa :D

 

Different strokes and all that I guess.....

 

Anyway, the ECU will do it's best to hold lamdba 1 (14.7 AF) when it's in closed loop and cams at low rpms shouldn't massively increase fuel consumption. But when you go open loop (85% throttle and / or 4000rpm), then things can start getting juicy.

5mpg isn't really a big enough drop to think there's anything seriously wrong.

 

You also haven't said which cams they are, so it's hard to gauge their characteristics.

 

Schimmel's cams have been shown to not increase mpg after a remap, yours hasn't been remapped yet. But his 263s are a rare breed indeed, more frugal than even the stock cams. Probably because of the very short overlap. Your 268s will have quite a lot of overlap.

 

And as Vince suggested, it's not unreasonable to consider the fact the engine may not be timed correctly, which throws off the sequential injector timing. I'm sure every attempt was made to get that correct, but it's easy to get wrong. Even the pros c0ck it up from time to time.

 

Iffy MAF sensors, lazy lambda probes, worn out plugs etc etc can all conspire against you to reduce mpg.....

 

I hope that was a little more helpful than yesterday's reply :wink:

[Toad 0]

You also haven't said which cams they are, so it's hard to gauge their characteristics.

 

They're shrick 268s.

 

And as Vince suggested, it's not unreasonable to consider the fact the engine may not be timed correctly, which throws off the sequential injector timing. I'm sure every attempt was made to get that correct, but it's easy to get wrong. Even the pros c0ck it up from time to time.

 

Iffy MAF sensors, lazy lambda probes, worn out plugs etc etc can all conspire against you to reduce mpg.....

 

I set the timing, not sure which smiley is appropriate here.... I fitted the chains, the upper chain cover and tensioner and turned the engine over by hand several times making sure the timing all lined up. When I was satisfied, we refitted the covers along with sealant etc, put the gearbox back on, refitted engine and span it over on the starter with no plugs for a while. I would assume that the late style tensioners would make the timing less likely to jump with the spring loading? Anyway, I'm quite happy to check the timing again.

 

i'd also like to give the senors a good going over, and see if any error codes are making a difference. Will be interesting to see it's mpg on a decent motorway run too.

[peanut 0]

i checked the timing afterwards mate and its was spoton in my opinion

Gav

[peanut 0]

I know this could be a long shot, but are the temp sensor plugs on the right way round?

pretty certain they are Stu but will check everything again! cheers for your helping hands on saturday too!

No worries John, didn't do a great amount comparatively speaking, apart from showing my legs :lol:

 

those shorts, lordy lordy....makes me feel dirty just thinking about it

Gav

[Toad 0]

No worries John, didn't do a great amount comparatively speaking, apart from showing my legs :lol:

 

those shorts, lordy lordy....makes me feel dirty just thinking about it

Gav

 

We forgot to tell him about the swingers program featuring his shorts on the telly after he went to bed! :norty:

[Kevin Bacon 5]

I set the timing, not sure which smiley is appropriate here....

 

This one? :scratch:

 

:lol:

 

Only kidding. You strike me as someone having more than an ounce of mechanical savvy.

 

I fitted the chains, the upper chain cover and tensioner and turned the engine over by hand several times making sure the timing all lined up. When I was satisfied, we refitted the covers along with sealant etc, put the gearbox back on, refitted engine and span it over on the starter with no plugs for a while. I would assume that the late style tensioners would make the timing less likely to jump with the spring loading? Anyway, I'm quite happy to check the timing again.

 

i'd also like to give the senors a good going over, and see if any error codes are making a difference. Will be interesting to see it's mpg on a decent motorway run too.

 

Good good. Sounds like it's OK then. Stealth get a LOT of botched timing jobs in their workshops, hence why he probably suggested it, but wouldn't know for sure without checking it. One guy was adamant his timing was 100% and almost took offense to Vince suggesting it wasn't. An hour later, it was evident the intermediate shaft was 90 deg out.

 

Anyway, keep an eye on it, mpg might improve as the ECU adapts. I can't remember what the mpg did when I had Schrick 268s unfortunately. It did seem to chew through more fuel though.

[Toad 0]

This one? :scratch:

 

Lol, yeah, but I didn't want to panic John at all... ;)

 

Good good. Sounds like it's OK then. Stealth get a LOT of botched timing jobs in their workshops, hence why he probably suggested it, but wouldn't know for sure without checking it. One guy was adamant his timing was 100% and almost took offense to Vince suggesting it wasn't. An hour later, it was evident the intermediate shaft was 90 deg out.

 

That's why I far prefer doing the timing with the flywheel and lower cover off. you can set the timing on all 4 shafts in one go, no fiddling around trying to spot the flywheel or serpentine pulley marks. Especially on a car with slightly stretched chains.

 

I didn't get a chance to look at the car again today, was a bit busier than I had imagined. :( Next weekend I'll give it a good ferreting over though :)