Where'd me power go??

[Mase]

Hello all - recently I added new cams to my May 02 build 172. Before fitting new cams I did base power runs and maxed out at 100 kw ATW & approx 160 Nm. Now here's the thing, 24 months prior I was consistently turning out 110 kw ATW and approx 180 Nm. So somewhere in those 24 months I dropped some power. Fitting the cams has added back in the 'lost' 10 kw but only 50% of torque...so back to 110kw & 170 Nm ATW.

Car has 2.5" catback, std 172 cat, wideband 02 sensor, std air box and panel filter. Custom mapping vai Henk. Nothing unusual on the logs both before fitting cams and after. Parameters all look fine. Car drives fine and feels strong. Cam PA's show extened pwr top end well into 7k's and good top end torque.

Just missing the 10kw before fitting the cams it seems. I should be seeing around 120kw / 180 Nm with the cams.

Engine doesn't use any oil and the oil stays remarkably clean for a long time after oil changes. Car is very well maintained.

Just wondering if people could offer advice as to what would be the 3-4 most common reasons to lose power and how to investigate? I know there are some very skilled and knowledgable people on this forum.

I haven't stuck me head up the exhaust as yet but of note she 'puffs' a little on idle..then again always has. No 'noises / rattles' from exhaust.

Cheers

 

[mx1_champ]

sure its defo timed up corect ?

 

[sideways danny]

same dyno? same weather conditions?

 

[Mase]

Yep timed up correctly. Nothing had changed between 110 kw and 100 kw (base run) prior to fitting cams except 24 months passed. I am using RSTuner PA. Testing done on same location essentially nearly the same weather conditions e.g 10 degs ambient, air pressure 1024 mb, no wind etc. Multiple passes taken and averaged.

Cheers

 

[Mase]

What about the cam dephaser solenoid? Do these ever cause issues? I have tested it via simple listening with the RSTuner however am not 100% that it is travelling full range and passing oil pressure. Henk said he had to 'deactivate' cam advance in the upper RPM to max power out of new cams which he said is unusual.

 

[sideways danny]

Henk said he had to 'deactivate' cam advance in the upper RPM to max power out of new cams which he said is unusual.

not really unusual

I personally think it's a difference in the dyno you're seeing (calibration or some such thing) and the car's as it ever was.

Worth checking your cat hasn't collapsed or been damaged/blocked though

 

[Andrew Cooke]

Worth checking your cat hasn't collapsed or been damaged/blocked though

given I'm running a PH1 how would I do this? is it a case of tapping with a coin, or do I really need to look inside with a boroscope?

 

[sideways danny]

tricky one. I've seen a number of 182 cats get a lot of cells blocked by contaminants, but never had a problem with 172's

 

[Andrew Cooke]

Doh on my part, I'm running a PH2 cat... not that it makes it any easier to check for damage.

have you ever fitted a pressure tapping before the cat?

 

[Mase]

not really unusual

I personally think it's a difference in the dyno you're seeing (calibration or some such thing) and the car's as it ever was.

Worth checking your cat hasn't collapsed or been damaged/blocked though

Yep that would be the easiest way to look at things

Re deactivation of cam advance Henk simply said normally there is no need to deactivate..I added 'unusual' comment. Got to whach my quoting!

 

[Tom@JMS]

Which cams out of interest?

For starters I'd carry out a leak-down test & check all the the ignition parts.

 

[Mase]

Going to leave the cams out of this discussion as I am trying to figure out what happened before fitting the cams. Otherwise it might descend into discussions about which cams are what / why etc.

So you think compression test and also check out coil pack, plugs, leads. Car drives fine though.

What I have noticed is that the speed data derived from the ECT is very choppy on the 6500.rst compared to when on the 6400.cal. I doubt this would effect engine running though.

MAP sensor is also a little erratic often being 20 mb out either way around what should be actual. Not sure if this wil effect engine output.

The other oddity is my Ave knock signal will gain itself up to about 30-40 @ idle after city driving for a few days.

 

[Tom@JMS]

Leak down, not compression; it was actually Henk who suggested it with one of our cars, far more precise than a compression test.

As already highlighted, the RR facility you are using - what sort of environmental compensation does it use, if any? and have you used the facility in very differing conditions? Out of interest were the power figures obtained using Henks software - it's incredibly accurate if used properly, but all it takes is the smallest error and it can make quite a difference to the figures.

Depending on your filtration/intake setup at full throttle and at a good speed you should see around 1020mb, (1025.3 mBar being atmospheric pressure (roughly)), say between 1015 - 1020 is about right - what are you getting? (just to note at fully shut throttle at a high RPM you will get around 165mBar.)

The increased knock would probably be due to increased inlet temps associated with low speed town driving, however no way of being certain. What sort of intake temps are you seeing on the screen? - too high (due to a faulty sensor maybe) and you will scrub some serious Ig advance and loose power.

 

[maupineda]

Going to leave the cams out of this discussion as I am trying to figure out what happened before fitting the cams. Otherwise it might descend into discussions about which cams are what / why etc.

So you think compression test and also check out coil pack, plugs, leads. Car drives fine though.

What I have noticed is that the speed data derived from the ECT is very choppy on the 6500.rst compared to when on the 6400.cal. I doubt this would effect engine running though.

MAP sensor is also a little erratic often being 20 mb out either way around what should be actual. Not sure if this wil effect engine output.

The other oddity is my Ave knock signal will gain itself up to about 30-40 @ idle after city driving for a few days.

This is an interesting finding of yours Jaime, I thought it was my sensor, never thought it was down to the rst version. This would affect the output of the PA in my opinion, as I take it derivates the torque from the acceleration and weight inputs, being choppy may affect the results I think. Any chance Henk can give you a version of your map for 6400 and try again?

 

[Mase]

@ Tom - I use the RSTuner PA feature. I am very careful how I use this. I have found it compares very well with RR's I have used withion about 1% error. Not bad! I'll check the closed throttle at high RPM later tonight. I generally see 14-18 mb pressure drop on MAP data from 2000-7000 RPM. At WOT at low RPM MAP is generally abour 15-20 mb below ambient pressures. Yes can see the Ave K rise due to air induction temps. My comments above seem to derive from a differing scenario as once learnt on ECU it pretty well stays that way until I reflash the ECU resetting the learnt data. Even after 1 hr driving in cold weather the higher Ave K hangs in there like poo stuck to a blanket!! I don't see higher SKC of FKC though which is interesting as higher RPM Ave K signals present normally...just seems to be a sensitivity thing at idle??

@ Mau - there is a alogorithm over the logged data for PA's that smooths out the fluctuations as I was advised by Henk. This seems to work well however do still seem some peaks / troughs etc. I wonder why 6500 creates a choppy speed data trace as I think you were saying yours is the same as mine??

 

[john lloyd]

earlier this year i found i had lost some bhp the torque/bhp curves looked right just but they were just 15bhp lower than they should afr was spot on with no faults being picked up on the diagnostics, turned out knock sensor was starting to get a bit lazy despite not logging a fault i swapped it with a new one and found my missing horses.

 

[Mase]

Now that's an interesting comment there John. My knock sensor has been doing some odd things of late. How did you know to target the sensor if you don't mind me asking?

 

[Mase]

Depending on your filtration/intake setup at full throttle and at a good speed you should see around 1020mb, (1025.3 mBar being atmospheric pressure (roughly)), say between 1015 - 1020 is about right - what are you getting? (just to note at fully shut throttle at a high RPM you will get around 165mBar.)

Hi Tom - here is the 1st pwr run when logging last weekend. Notice the ambient reading drops rapidly at WOT. Now the actual ambient would have been 1020 mb where I was. The MAP over the run lost 14 mb from start to end. All parameters look fine re advance etc doing around 28 deg at 6K > Kc kicks in around 5-6K rpm but maxes out at 2.25 only occasionally. Thoughts?

Uploaded with PostImage.orghttp://www.postimage.org/image.php?v=Tsz0ma0

 

[john lloyd]

it was on a rolling road day the operator on the day looked at the maps he knows the engine spec and he has had dealings with renault cup race series support he used his knowledge and said maybe worth changing, stuck a new one on £35 from dealers and went back a few months later and my bhp was back, gained about 15bhp.

hats of to the chap though as no fault codes or anything he had just seen this before when working with renault in the race series and doing mapping for them so he made an eductaed guess based on the way the car drove and the maps.

 

[Mase]

Thanks John. Food for thought. My knock signal 'looks' fine on the RSTuner but sometimes does a few odd 'gaining' up and down actions but could be normal. Henk seems to see nothing unusual. I'll keep an eye on things.

35 pound for a knock sensor I bet here in Aust they are 8 times the price!!

Cheers