Crackling noise around 5-6k rpm
Discussion
I am experiencing a problem with my Mini Charged 5 at the minute where i am getting a crackling noise, sort of like small stones hitting the arches, at between 5-6k rpm.
This has only happened the past couple of weeks when it has got warmer, the month or so i was running my car before this noise wasnt there and nothing has changed on my map.
I have tried making the car a bit more retarded to get the noise to disappear as i though it could be something to do with that, but it needs about 3-4 degrees more retard before it disappears, which seems far too much!
Has anyone else had this noise, and if so what was causing it?
For reference the follow is my ignition table at 135kpa, so 5psi boost, and each number being minus from the standard 10 degrees timing
RPM 4800 5200 5600 6000 6400
Retard -11.88 -12.63 -12.13 -11.38 -11.63
Just so people have an idea what things are set to, AFR's are around 11.5.
Thank you in advance for any help! I have posted this on mx5nutz aswell, just thought i would try here as i know there are a few who might be able to help
This has only happened the past couple of weeks when it has got warmer, the month or so i was running my car before this noise wasnt there and nothing has changed on my map.
I have tried making the car a bit more retarded to get the noise to disappear as i though it could be something to do with that, but it needs about 3-4 degrees more retard before it disappears, which seems far too much!
Has anyone else had this noise, and if so what was causing it?
For reference the follow is my ignition table at 135kpa, so 5psi boost, and each number being minus from the standard 10 degrees timing
RPM 4800 5200 5600 6000 6400
Retard -11.88 -12.63 -12.13 -11.38 -11.63
Just so people have an idea what things are set to, AFR's are around 11.5.
Thank you in advance for any help! I have posted this on mx5nutz aswell, just thought i would try here as i know there are a few who might be able to help
5-6k is peak torque so the most likely range to get pre-ignition and that sounds like what it is.
It has been unusually warm lately and without an IC it might well cause you a problem.
You should check things over to make sure there isn't anything else causing it though. Check all 4 plugs for gap and colour.
Do you know for sure your injectors are clean, clear and working well?
Better check the timing too i.e. that the timing marks are correct. Remove the spark ug from cylinder 1, put a cane or similar down the hole and turn the engine to check that the TDC mark really is TDC then make sure the base timing is correct. If these are out you are shooting in the dark.
It has been unusually warm lately and without an IC it might well cause you a problem.
You should check things over to make sure there isn't anything else causing it though. Check all 4 plugs for gap and colour.
Do you know for sure your injectors are clean, clear and working well?
Better check the timing too i.e. that the timing marks are correct. Remove the spark ug from cylinder 1, put a cane or similar down the hole and turn the engine to check that the TDC mark really is TDC then make sure the base timing is correct. If these are out you are shooting in the dark.
Don't have an intercooler at the minute, but plan to get one in the near future
I have only just fitted new spark plugs as i got a set that were a step colder during the week wondering if it could possibly be those, but that didn't fix it! I took them out this morning to see what their appearance was like, and over the 50 miles they have covered i seem to have a black sooty appearance on them. According to my workshop manual this normally means that it is running rich....which is odd because it isn't as far as i can see!
Also when i took the car out for a drive this morning, i noticed that the crackling was back, with the ignition table i posted in the OP. This is starting to worry me a bit now. The car was fine when the above was 4 degrees less, then fine with it above, now it has appeared again :\
I have only just fitted new spark plugs as i got a set that were a step colder during the week wondering if it could possibly be those, but that didn't fix it! I took them out this morning to see what their appearance was like, and over the 50 miles they have covered i seem to have a black sooty appearance on them. According to my workshop manual this normally means that it is running rich....which is odd because it isn't as far as i can see!
Also when i took the car out for a drive this morning, i noticed that the crackling was back, with the ignition table i posted in the OP. This is starting to worry me a bit now. The car was fine when the above was 4 degrees less, then fine with it above, now it has appeared again :\
Just been out again with a few tweeks to the map. I advanced the ignition by 4 degrees as it obviously wasn't having an effect running so retarded. I also added 2% more fuel between 4800-6800. Amazingly the crackling has now gone, and i was being a lot more brutal with it than i was this morning!
Until you can data log it I'd avoid boost altogether. Seriously. If you can hear the knock that easily then it's serious enough to be damaging your pistons. Listening for knock is a very bad way to tune. You really need det-cans so you can do it properly. Personally I got the timing map done for me on a rolling road. I told them to concentrate on getting the timing map right as I can fine tune the fuel map myself but timing is something I'd rather not touch.
At full load I'm aiming at 11. I'm probably running slightly more power than you though.
I wouldn't trust using someone else's map. I have a mate with an almost identical setup to mine. His map bears no relation to mine at all. I can run a lot more timing at low & mid range whereas he runs more at high revs. Both cars have been rolli g road tuned. I reckon if we swapped maps it would quickly kill both cars.
No 2 cars are the same. You can use a known good map from a similar car as a base map but only to give you a starting point. I wouldn't use it as a road map, especially the timing map.
I wouldn't trust using someone else's map. I have a mate with an almost identical setup to mine. His map bears no relation to mine at all. I can run a lot more timing at low & mid range whereas he runs more at high revs. Both cars have been rolli g road tuned. I reckon if we swapped maps it would quickly kill both cars.
No 2 cars are the same. You can use a known good map from a similar car as a base map but only to give you a starting point. I wouldn't use it as a road map, especially the timing map.
couple of things that will lessen or stop the detting altogether is making sure you're using 99RON fuel and fitting an intercooler. The intercooler will be the most helpful thing you can do.
Your air intake temps are too high hence the detting in warmer/hot weather. Fit that and you can add your timing back and run a bit leaner for more power/economy.
ETA: 11.5 afr at peak power should be perfect on most FI motors.
P.S. I tune Subaru Impreza but FI is FI whatever the motor. If you have the software and cable i have a wideband and detcans and i'm in Northamptonshire. When you get am intercooler fitted give me a shout and i'd be happy to help out FOC. There's no point you messing too much with your mapping because ambient temps will change fueling anyway so when it cools you'll run richer and vice versa when warm/hot. Once you start getting ambients of 16degC and above most FI motors will start losing power. Keep it mapped safe, rich and not huge amounts of timing and drive it with sympathy and you'll be fine till you fit the intercooler which should be your main priority.
I've got a feeling you might be using RomRaider/ECUflash/ECUedit. I know my way around those mapping tools intimately so if that's what you use it makes the job even easier.
Good luck
Your air intake temps are too high hence the detting in warmer/hot weather. Fit that and you can add your timing back and run a bit leaner for more power/economy.
ETA: 11.5 afr at peak power should be perfect on most FI motors.
P.S. I tune Subaru Impreza but FI is FI whatever the motor. If you have the software and cable i have a wideband and detcans and i'm in Northamptonshire. When you get am intercooler fitted give me a shout and i'd be happy to help out FOC. There's no point you messing too much with your mapping because ambient temps will change fueling anyway so when it cools you'll run richer and vice versa when warm/hot. Once you start getting ambients of 16degC and above most FI motors will start losing power. Keep it mapped safe, rich and not huge amounts of timing and drive it with sympathy and you'll be fine till you fit the intercooler which should be your main priority.
I've got a feeling you might be using RomRaider/ECUflash/ECUedit. I know my way around those mapping tools intimately so if that's what you use it makes the job even easier.
Good luck
Edited by ScoobieWRX on Friday 3rd August 23:17
I don't disagree with any of that. MX5 engines tend to run better slightly rich though so aiming nearer to 11 at peak torque & WOT is better. An IC is a good idea but an MX5 engine is ok for 5-6psi and approaching 200bhp without one.
He is using an AEM FIC which I think is a piggy-back ecu and will have its own software for mapping. MX5s don't have remappable ecu so we don't use ecu flashing software.
Good of you to offer your help to OP though
He is using an AEM FIC which I think is a piggy-back ecu and will have its own software for mapping. MX5s don't have remappable ecu so we don't use ecu flashing software.
Good of you to offer your help to OP though
I've just had a look at the AEM FIC and he's got three adjustable parameters. Ignition, Fuelling and MAF recalibration, plus he can log AIT's.
I think one of his fuelling problems stems from needing to recalibrate/rescale the MAF sensor rather than messing with the fuelling tables all the time.
Equally he could do with running an AIT sensor after the turbo/before the throttle body to get accurate AIT temps. If his MAF sensor is just after the air cleaner and doesn't have a built in AIT sensor (if AIT is separate to MAF will probably somewhere very near to the air cleaner anyway) he could locate and move the AIT sensor to where i've suggested. Might be able to control AFR's better that way but even then he is really limited to what he can adjust.
I imagine he's running some kind of after market induction kit and got rid of the factory airbox/cleaner in which case proper MAF scaling is essential if he can do it.
I think one of his fuelling problems stems from needing to recalibrate/rescale the MAF sensor rather than messing with the fuelling tables all the time.
Equally he could do with running an AIT sensor after the turbo/before the throttle body to get accurate AIT temps. If his MAF sensor is just after the air cleaner and doesn't have a built in AIT sensor (if AIT is separate to MAF will probably somewhere very near to the air cleaner anyway) he could locate and move the AIT sensor to where i've suggested. Might be able to control AFR's better that way but even then he is really limited to what he can adjust.
I imagine he's running some kind of after market induction kit and got rid of the factory airbox/cleaner in which case proper MAF scaling is essential if he can do it.
Being a fairly simple piggy-back ecu the AEM won't be doing anything at all out of boost. That means the stock ecu will be controlling everything at idle and cruising which is where air temp makes the biggest difference.
In boost the AEM will be sending a clamped stoich signal to the stock ecu so that fuelling can be completely controlled by the AEM. In boost the air temps will make a bit of a difference to the ideal fuelling but in reality very little so the mapping should just be made "safe" to give a bit of headroom in case of extreme weather conditions which should be standard practise anyway. The only reason to tune to get absolutely every possibly bhp would be for drag strip running or bragging rights at the pub.
In boost the AEM will be sending a clamped stoich signal to the stock ecu so that fuelling can be completely controlled by the AEM. In boost the air temps will make a bit of a difference to the ideal fuelling but in reality very little so the mapping should just be made "safe" to give a bit of headroom in case of extreme weather conditions which should be standard practise anyway. The only reason to tune to get absolutely every possibly bhp would be for drag strip running or bragging rights at the pub.
MX-5 Lazza said:
Being a fairly simple piggy-back ecu the AEM won't be doing anything at all out of boost. That means the stock ecu will be controlling everything at idle and cruising which is where air temp makes the biggest difference.
In boost the AEM will be sending a clamped stoich signal to the stock ecu so that fuelling can be completely controlled by the AEM. In boost the air temps will make a bit of a difference to the ideal fuelling but in reality very little so the mapping should just be made "safe" to give a bit of headroom in case of extreme weather conditions which should be standard practise anyway. The only reason to tune to get absolutely every possibly bhp would be for drag strip running or bragging rights at the pub.
Sitting idle on a hot day temps can rise quickly so the ECU's AIT fuelling comp table changes fuelling as temps rise. In closed loop mode on cruise the ECU is trying for as close to Stoich as it can get and AIT's although they will generally be low anyway will still make some difference but not a lot. MAF sensor is the overiding controller together with the MAP and Lambda sensor on closed loop. In boost the AEM will be sending a clamped stoich signal to the stock ecu so that fuelling can be completely controlled by the AEM. In boost the air temps will make a bit of a difference to the ideal fuelling but in reality very little so the mapping should just be made "safe" to give a bit of headroom in case of extreme weather conditions which should be standard practise anyway. The only reason to tune to get absolutely every possibly bhp would be for drag strip running or bragging rights at the pub.
An AIT compensation table for fuelling will make the biggest difference on boost as AIT's rise rapidly but this piggyback doesn't run one. I presume it clamps the MAF as well and runs SD type tuning rpm(rows) x MAP (columns) for engine load so MAFless in effect.
True AIT's after the turbo do rise significantly on boost and especially so without an intercooler so it's better for your engine if the ECU reads AIT's after the turbo so it can fuel more accurately however, this piggyback isn't doing any of that. Although it lets you log IAT's it's not controlling any of the fuelling based upon that. It just runs a fixed rate of fuelling that you set at x-rpm/MAP and that's that regardless of AIT.
Does this piggyback pull timing if you get knock, no it doesn't and i presume neither does the main ECU because it's out of the loop effectively on boost so if you get a very lean patch top end for whatever reason it's goodbye engine. No knock control and no AIT fuelling comps either.
I hope the OP has got or finds a way of monitoring true AIT's at least separately and in conjunction with a wideband to set fuelling correctly as he goes along.
As for running an intercooler for higher boost, timing etc...It's not about more bhp or bragging rights it's about dialling in more torque low to mid range which makes for a very quick car around any track or street. If you're doing 1/4 miles runs all the time fine map for peak power but i presume this car is driven normally on the street and does the odd trackday only so more torque is desirable and makes the car that much nicer to drive generally regardless of what it is.
An example is your average GrpN Subaru only running 300bhp but torque levels are over 550-580ftlb from 2000rpm.
You obviously know what you are talking about and if it was my own car then you would be right on the money (supercharged, IC, Adaptronic ecu, AIT, MAP etc. and with power up by around 100bhp over stock) but what you have to bear in mind is that this is a budget car (MX5s are very cheap now) with budget FI and a budget fuel/timing solution. The power increase is modest and the engines are actually built for FI. The stock ecu is fine for running out of boost and in boost will run to its built in fuel & timing maps. It's still getting all sensor inputs including the stock AIT reading ambient temps. The O2 is clamped so it thinks what it's doing is spot on and doesnt try to mess with anything. The AEM will intercept the injector signal and add/subtract a percentage to the injector duration up to a max of +100%.
I believe the stock ecu itself runs purely from maps over certain revs (4k?) and at WOT so isn't reading the MAF or AIT. The base timing is very conservative and they tend to run a little rich (hence poor economy for a small light car). A piggy back ecu is never meant to be the final solution but can be tuned to be very effective as long as the limitations are kept in mind and you don't push them too far.
I believe the stock ecu itself runs purely from maps over certain revs (4k?) and at WOT so isn't reading the MAF or AIT. The base timing is very conservative and they tend to run a little rich (hence poor economy for a small light car). A piggy back ecu is never meant to be the final solution but can be tuned to be very effective as long as the limitations are kept in mind and you don't push them too far.
Totally agree with all of that. With the cars being that cheap there must be some budget leftover for a proper aftermarket ECU.
I'm not up on Mazda at all and for all i know there may well be a good solution for them. Maybe Autronic, Haltech, Omex that kind of thing.
I genuinely wish the OP a shedload of good luck sorting out his car. If he gets stuck he's more than welcome to give me a shout. Good chatting with you Lazza.
Cheers all
Francis
I'm not up on Mazda at all and for all i know there may well be a good solution for them. Maybe Autronic, Haltech, Omex that kind of thing.
I genuinely wish the OP a shedload of good luck sorting out his car. If he gets stuck he's more than welcome to give me a shout. Good chatting with you Lazza.
Cheers all
Francis
ScoobieWRX said:
I'm not up on Mazda at all and for all i know there may well be a good solution for them. Maybe Autronic, Haltech, Omex that kind of thing.
There's loads of decent options for the MX5, Adaptronic and MegaSquirt are two examples that can be available PnP. For the MegaSquirt, any variant will do, but MS3 with the MS3x card is the latest and greatest. For the OP a cheap and cheerful home built MS1 will far outperform the AEM FIC.Gassing Station | Mazda MX5/Roadster/Miata | Top of Page | What's New | My Stuff