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09-18-2012, 05:08 AM | #1 |
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Flat spot on N52 engine for 130i
I have a flat spot when accelerating in any gear. It starts anywhere between 3800rpm and 4500rpm, it does it for about 1000rpm.
The history of the car is that it was standing for months since the accident and while getting repaired…. It only had body damage on the whole left hand side, the only mechanical damage was the air filter box…. Once I got the car back from the repairs, 2 days later I had the 60000km service (replaced the filters, oil, brake pads, etc) and decatted the exhaust. Since I’ve had the car back, I’ve had the flat spot. The flat spot either got caused by standing for months or when they did the decat…. The car has been at BMW, and a few other service workshops, for the diagnostics test, OEM software update, new oil and filters again, sensors checked, etc. The only 2 things they didn’t do is open up the engine and the VANOS. Even tried aftermarket tuning software and the BMS Power Box. With either of these, there was no power gains at all, and the flat spot was a lot worse… Went back to latest OEM software.... The decat and K&N filter (fitted 4 years ago) is now the only mods done. The flat spot feels like its battling with the air/fuel mixture or the suction of the fuel line. What do you think is causing it? At the moment, I either have to change down or up a gear to get the revs below 3800rpm or higher than 4500rpm to accelerate
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09-18-2012, 06:38 AM | #3 |
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Typically on NA engines, decat will cause some torque loss mid rpm range, but power gain in higher rpm...So it might be normal...
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09-18-2012, 09:08 AM | #4 |
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They removed both sets of Cats, by the manifold and the 1 silencer.
Its not normal though, some other members in our club, have done it on their NA engines and dont have this problem
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09-18-2012, 09:20 AM | #5 |
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Maybe your DISA valve (inside the intake manifold) is all junked up with oil and crud. You might want to run a can of LIQUI MOLY throttle valve cleaner thru the intake tract.
http://www.liqui-moly.de/liquimoly/w...archive48.html PS: are you spark plugs Ok/new?
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09-18-2012, 09:27 AM | #7 |
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So the next step is to test the DISA valve.
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09-18-2012, 09:33 AM | #8 |
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We've done that. Made no difference
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09-18-2012, 10:12 AM | #9 |
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I wonder IF camshaft timing could be an issue. Maybe check the vanous if its working properly.
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09-18-2012, 01:47 PM | #10 |
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the flat spot could be the large DISA valve being slow to open, especially since tunning didn't work.
Try unplugging all the DISA conections, leaving them all open and see how it behaves. Perhaps that could rule out Disa and make you think Valvetronic not opening or throttle body issue, also not opening wide. Valvetronic & other sluggish issues has been discussed in e90post n52 section recently
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In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff "The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is |
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09-18-2012, 01:51 PM | #11 | |
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I see you edited your post Will try the unplugging idea
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09-19-2012, 05:54 PM | #12 | |
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09-25-2012, 10:42 AM | #13 |
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Had the car at another workshop today. They checked everything and can't find the cause of the flat spot. The diagnostics didn't find any errors either.
It's puzzling at what's causing the flat spot if no workshop can find the problem I've booked it in again at BMW for Thursday. Told them to keep the car till they find the fault
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09-25-2012, 11:24 AM | #14 |
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that RPM range is the Large DISA open point do it has to be something about air flow.
- Throttle body malfunctioning @ that point - Valvetronic map enters a new stage at that point, due to new DISA state. Since when tuned it was worse, this could be it. If you have a shop & time. Maybe take off manifold, connect Throttle body on its own on the side and rev the engine. You should see Throttle body opening & the valves opening. Like the n52 530i youtube video w/out manifold Although this is alot of work only to see flaps move...
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128i Sport 6MT converted to Euro 130i spec, 3.73 diff, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE
In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff "The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is |
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10-01-2012, 08:57 AM | #15 |
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Had the car at another tuning place today. They found the fault thats causing the flat spot. Its the accelerator pedal module.
Its loosing voltage from 5 volts down to 2 volts during the acceleration between 3500rpm and 4300rpm. Pic of pedal module on Realoem Finally the flat spot has been resolved, after months of being at a few places to find the fault. Thanks for your help guys, for what you suggested I should try
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10-10-2012, 08:30 PM | #16 |
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how many Km on your car. This is the first ive heard about this issue e90/e82
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128i Sport 6MT converted to Euro 130i spec, 3.73 diff, tuned by evolve ~220 whp 207 wtq(ft-lb) SAE
In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff "The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is |
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10-11-2012, 12:36 AM | #17 |
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It has 65700km now. The flat spot started months ago, the Km's then was just over 58500km.
The module hasn't arrived yet, from Germany. Will keep you guys updated once its installed and driven for a few km's
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10-12-2012, 08:02 AM | #18 | |
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10-15-2012, 02:44 AM | #19 |
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It is interesting that this module is faulty, never heard/seen this happen before. In our currency (South African 1700 Rands / About 150 Euro). No, there wasn’t any faults stored, that’s why BMW themselves couldn’t find the problem. The tuner had 3 different diagnostic systems, only the 1 found the problem.
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10-18-2012, 05:45 PM | #20 | |
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Auto Atlantic has had my 330i since Monday (got her back this afternoon) and than ran diagnostics a number of times but could not find any faults, and I mean anything! ART found that there was a fault with the two DISA Flaps, the thermostat, and the Valvetronic motor (10% out of spec). Now this is not to say that these items are not functioning or totally faulty, but they picked up irregularities that are causing the strange pinking type noise and so on. I reckon the strange dip in power between 3000 - 4500 rpm is being caused by the issues with the DISA Flaps. Point is, the agents are only capable of finding the obvious and easy faults, so as far as I am concerned, they are just plain useless at sorting out these more complex issues - so motorplan or warranty is pointless. For the benifit of other members, this 130i M and 330i are friends and we are talking about the same tuner with regards to the diagnostics - very jacked up crowd, so they know what they are doing and meticulous as opposed to running a sausage factor expected to turn around 80 plus cars a day! And this is the biggest problem with the agents - they just don't spend as much time as needed when tackling these more tricky issues. Hope 130i M gets her shiny new throttle pedal module soon! Last ditch effort for BMW - have a meeting with a technical rep from BMW SA with regards to my car's issues, but can just see more time is going to be wasted. |
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10-19-2012, 03:02 AM | #21 | |
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ART found other faults with my car which they want to examine, like the power output. I showed them all my dyno result printouts (about 9 graphs) that I’ve done the past 4 years at “dyno day” events. The avg power readings on the graphs was in the low 170’s instead of in the high 180’s / low 190’s. Most of the graph readings are done at the flywheel. The BMW spec of the engine is supposed to be 195kW. My engine is performing like the E46 3l engine which is spec’ed at 175kw. ART is gonna examine this once the flat spot is sorted. I got the module yesterday from Auto Atlantic, installed it last night. Took the car for a drive afterwards for about 20km’s. The flat spot is a lot better, it happened 7 times, instead of most of the gear changes within the rev range 3800 - 4500. Gonna see how it performs over the weekend. There’s 2 dyno day events tomorrow, will put the car on both dyno’s to see how the flat spot looks on the graph. It will be a minor drop now. Will get my dyno graphs later, to put here so that you guys can see how bad the flat spot was
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10-29-2012, 10:20 AM | #22 |
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I've had the pedal in for 10 days now. It still has the flat spot but not as bad as what it was.
I've checked with ART today, they said that the new pedal module needs to be programmed into the system. I thought it was just a "plug n play" Below are the dyno graphs that were done this year. The decat and K&N filter mods were in all 3 graphs. The flat spot only kicked in on the 3rd graph. Luckily it didnt kick in, in the first 2 graphs. The first 2 were done on the same day. This pic was with the BMS Power Box map: This one is with OEM map, notice the increase of power: This one is 6 weeks later with other software:
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