View Full Version : Turbo efficiency
Today on a private road I noticed that around 100mph with WOT the engine gets very hesitant...kind of pulsing power on a off but not really going much faster. It made me wonder whether this is the turbo just not being strong enough for the amount of boost I have it set to run on. I have the Squadra chip and a manual boost controller which I think it set to around 1.3 bar, although I do get some bleed off (can't find a leak, might be the IC)
I think it is either the turbo not being able to cope any more although it still does pull very hard and quickly from 3-5000 rpm. Or it may be some ignition problem that only comes about when under high load. I have the NGK B8EGV spark plugs fitted.
Any thoughts on this?
Thanks,
Jack
arjunior45
10-02-10, 09:29
Did you do this test {100 mph and wot} in 5th gear?
If yes try the same test with lower gear {3rd / 4th} and report.
1.3 bar is too much for the stock turbo to work efficiently, however it wont cause it to "pulse" like you describe. That is definitely a tuning issue, most likely an ignition missfire but it really could be anything, fuel pressure etc (which would not be good).
B8EGV is the wrong plug in my opinion. A racing plug that is too cold.
I have noticed a similar phenomenon. If you upgrade inlet, exhaust etc. and also use a bleed valve, the boost pressure will be much higher than with stock setup. At a certain point in the boost map (somewhere 4500-5500 rpm) you may reach the boost limit. I don't know how the boost limit v.s. rpm is set in by Squadra, but it might be the problem i describe.
I totally agree with SteveNZ regarding B8EGV. I have a set, but don't use them. Denso's Irridium plugs are the ones with highest recommendations by hardcore Integrale experts. I haven't tested them myself.
arjunior45
10-02-10, 16:58
I use B8EGV with oem chip/eprom for more than 2 years now without problems at all.
I fitted these to help a big hesitancy after I had fitted the manual boost controller and turned the boost up a bit. It solved that problem but perhaps this is the downside.
What engine setup are they better suited to?
jimnielsen
10-02-10, 19:48
Jack, I use the B8EGVplugs as well. I have been very happy with them. I think that your problems most likely stem from fuel issues as the system is pushed hard. I would not put the car in this situation if possible. It would be good to either get a wide band lambda sensor and display - that can be had very cheaply these days - or a dyno run - that would probably be more expensive and you only get to do it once..
http://cgi.ebay.com.au/INNOVATE-DB-Red-Gauge-LC1-Lambda-Cable-O2-Sensor_W0QQitemZ180467832167QQcmdZViewItemQQptZAU_ Car_Parts_Accessories?hash=item2a04b89567
Jack, you may recall a recent thread on 155.org where I asked about plugs, TEJ (knows all about plugs!) suggested BPR7EIX up to around 240bhp and BPR8EIX for 300bhp.
He also said the B8EGV plugs were too cold...
wrinx
does it eventually pull through or is it stuck "pulsing"?
what kind of rpm is this at?
this pulse is like the rpm limiter when it appears ?
Jack, you may recall a recent thread on 155.org where I asked about plugs, TEJ (knows all about plugs!) suggested BPR7EIX up to around 240bhp and BPR8EIX for 300bhp.
He also said the B8EGV plugs were too cold...
wrinx
I've always taken a special interest in plugs too. First I'd just like to say that as long as you have a plug, any plug really, in good condition in the correct heat range your engine should run fine for the majority of uses. The minor differences there are in plugs do have minor effects though and I like to get the right one in there or at least the one designed for the engine in the first place.
Fitting a racing version of this plug or a plug with advanced features, special materials etc and fine and up to you (these are represented by the suffix in the part number). But this is not what I'm here to discuss. I believe you should still keep with the correct/original type of plug design (represented by the prefix). If you are going to use a different plug, I believe you should have a very sound reason to do so.
B8xxx and BPR8xxx are the same heat range. Good for racing around a track with 300+HP but too cold for the majority of normal driving.
BPRxxx is of the original design type as specified for the engine, hence I would and have used it. "B8xxx" is a different type of plug. This plug is commonly found in 2 stroke motorbikes and I know from memory, they have a very short protrusion into the cylinder and no doubt other differences. It's also not a resistor plug. Which may or may not cause issues in some engines.
"EGV" suffix is just the racing version of the standard plug "es". These were basically the best on offer 20 years ago, I ran a B9EGV in my 2 stroke race bike back when I was a teenager. You could however use a B8EV which is a cheaper version or even a B8ES which is standard. These are just like the different range there is today, platinum (VX), iridium (IX) etc
Now 20 years ago when people stated tuning these engines there was not a large range of different plugs in the original series so I think the tuners went looking elsewhere for a suitable "racing plug" that would work. They of course found the B8xxx series and used it because it was the best on offer at the time, and worked, maybe solved some minor issues they had with the stock copper "fat stub electrode" plug.
I think the knowledge of these old plugs used years ago has dribbled down the forums of the world for a long time and it has become a common knowledge that these are the plug to use. But these plugs are basically out of date now. Advanced versions of the original type plug are available. There are so many different choices I don't see the need to use the old 2 stroke plug anymore.
IMHO BPR7EIX is probably the plug they would have chosen if it was available 20 years ago. But you don't need to use that one specifically. I have used plain old BPR7ES without issue and BPR7EVX for longer life. I have also used V electrode, tripple electrode, quad elecrode, suface discharge, all claiming different benifets but TBH I've never noticed any difference.
That's a great write up, nice one.
arjunior45
13-02-10, 07:10
I agry, especially these last words :
- "but TBH I've never noticed any difference."
IMHO BPR7EIX is probably the plug they would have chosen if it was available 20 years ago. But you don't need to use that one specifically. I have used plain old BPR7ES without issue and BPR7EVX for longer life. I have also used V electrode, tripple electrode, quad elecrode, suface discharge, all claiming different benifets but TBH I've never noticed any difference.
BPR7EIX was suggested because of its longer life characteristics, being Iridium. Stuck them in the Q4 and it does run better. The previous plugs were almost new so a good comparison imho.
I plan to use the 8 range after a new turbo and remap are completed, 300bhp is the aim.
wrinx
does it eventually pull through or is it stuck "pulsing"?
what kind of rpm is this at?
It will go faster but it just sort of starts stumbling and feels hesitant. It is quite hard to describe and I don't get the opportunity too often. I think if I went at 85% throttle it might go better through this stage.
90% of my driving only causes me to use low to mid range power so I only get to notice these problems occasionally.
@Jim, thanks, yes I think I do need to get one of these AFR gauges. These digital displays though, how fast do they keep up with the contact change? Would it be better to get one with a dial like a boost gauge instead?
@SteveNZ, thanks for the write up. I may have to swap these out at some point then during the fault finding.
Just remembered something which might be key to this. The Squadra chip specifies that I should use RON98 fuel but was the past 4 or so years I have used RON95:tapedshut: Could it be contributory to the problem or would I simply be down on power?
The Squadra chip specifies that I should use RON98 fuel but was the past 4 or so years I have used RON95:tapedshut:
I also have used RON95 with the Squadra chip. :tapedshut: Never had any problems. Only thing I ever noticed, was less power.
Greetings,
Marc
If its designed to run 98 it could be picking up some detonation on 95. It will show up more on long power runs where the engine is working hard and heating up. If it does the management will probably knock 3 degrees of the advance (usual Fiat thing) until the detonation is not detected. This could be noticeable.
First: Steve, a very good historical background to the B8EGV myth. Thnaks.
then: You guys who have used RON95 with the Squadra chip, have you ever checked the condition of the pistons tops through the spark plug hole? With several years of use it would be an excellent test. In theory you should see damage since it doesn't retard ignition until knocking has occured and that means there has been a lot of dangerous detonations after years of use. Just curious.
Rearding fuel supply as a factor in the problem we discuss. It could be, but I have expecrienced similar problem with a high flow Walbro 355 (?) pump installed, so I would guess it is not the most likely problem.
then: You guys who have used RON95 with the Squadra chip, have you ever checked the condition of the pistons tops through the spark plug hole?
No I didn't checked this. I have a combi-prom and am able to change back to the original chip. Normally I use RON98.
About the dammage I can;t tell until it will be taken apart soon.
Greetings,
Marc
then: You guys who have used RON95 with the Squadra chip, have you ever checked the condition of the pistons tops through the spark plug hole?
I can't say I have but will try and see next time although I think it will be pretty difficult. Am I looking for sort of pitting in the piston?
I have not done any testing of anything yet but found that it was not giving me this hesitancy yesterday but it did got to 120 but wouldn't go much futher. Boost was at about 0.75. Maybe it is the wastegate failing.
air leak between turbo and engine?
tired fuel pump? pressure tailing off...
I also had sometimes hickups, mostly higher in the revs. These came from the two relais against the plate between engine and passengers. One of them was not always making contact. Only found the source of the problem when it totaly gave up.
Just over the strutbrace, if you got one fitted, they are next to each other.
arjunior45
23-03-10, 06:17
could you post a picture of them? If i understood well, one fo those two relais is the one for the injection?
I borrowed a picture from a faster Q. But location is the same.
http://i43.tinypic.com/5lb4hy.jpg
Them failing a bit would cause a drop in fuel pressure.
I've known those relays and the loom to them to cause a complete breakdown that took forever to find. They seem to be the first to suffer the ageing looms this old suffer. I'd check what the pressure was doing at full engine load.
Juan AR155Q4
26-03-10, 14:53
I think one of those relays is for the fuel pump.
One for fuel pump relay and the other for injector control.
wrinx
arjunior45
27-03-10, 15:34
Yes, I thought they were the one.
Strange symptom the 'hickups'!!!!
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