Running a DDM Stage 1 set up having a issue now and then when racing. If I shift at a high rpm let’s say 5k+ to fast the engine will stumble and fall on its face. If I accidentally hit red line and shift forget it the engine sounds like it dropped a spark plug or two. Then comes back to life after a few seconds. Other day happened so bad I had to clutch in to idle cause I thought I blew the motor but after releasing clutch back out she was fine. I have temp, A/F and Boost gauges installed all read good readings at all times. The only thing I caught was during the bad stumble when i clutched in the A/F instead of dashing out I noticed it hung around 17 for awhile as Rpm’s dropped which didn’t alarm me much but was different. I changed the spark plugs and had just replaced battery so I did a ecu reset. The Stumble will Still happen if I go to hard. Anybody having this type of issue or have any ideas for me to try. Thought maybe the BOV needs some adjusting like the charge is not releasing between gears fast enough and overloading the intake with air but I’m not very BOV knowledgeable. Thanks for any help
Turbo/Engine bog at fast shift?
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Dave@DDMWorks - - ??
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Running a DDM Stage 1 set up having a issue now and then when racing. If I shift at a high rpm let’s say 5k+ to fast the engine will stumble and fall on its face. If I accidentally hit red line and shift forget it the engine sounds like it dropped a spark plug or two. Then comes back to life after a few seconds. Other day happened so bad I had to clutch in to idle cause I thought I blew the motor but after releasing clutch back out she was fine. I have temp, A/F and Boost gauges installed all read good readings at all times. The only thing I caught was during the bad stumble when i clutched in the A/F instead of dashing out I noticed it hung around 17 for awhile as Rpm’s dropped which didn’t alarm me much but was different. I changed the spark plugs and had just replaced battery so I did a ecu reset. The Stumble will Still happen if I go to hard. Anybody having this type of issue or have any ideas for me to try. Thought maybe the BOV needs some adjusting like the charge is not releasing between gears fast enough and overloading the intake with air but I’m not very BOV knowledgeable. Thanks for any help
Hey there, you would want to check around all the exhaust connections. From the information you gave, it sounds like you will find a small exhaust leak, most likely between the header and the exhaust (3 bolt connection). There might also be a leak at the cylinder head connection to the header also. When there is a leak at one of those connections, under light throttle especially, air gets pulled into the exhaust system. That air hits the oxygen sensor and the ECM then thinks that the engine is running lean, although this is a false lean condition caused by the air getting into the exhaust. Since the ECM thinks that the engine is running lean, it adds more fuel via fuel trim, which makes the engine run richer than it normally would. I would also pull your oxygen sensor and see if it is pretty black, if so, that is probably what is going on.
Take a look at all of that and let me know what you find. Feel free to send a message here, but you can also email me direct - Dave@ddmworks.com, give us a call during the day 864-438-4949 or reach us after hours on the techline 864-907-6004.
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Thank you will definitely take a look over the weekend at what u mentioned. I have the o2 sensor installed in the 1320 header port before turbo and A/F sensor in the port on the ddm race exhaust after turbo. I read recently I prob should have swapped them due to heat reasons but only seen it talked about once so wasn’t sure it was a real thing or not. I will investigate and get back. Thanks again
Sounds good, remember you can call on the weekends also, happy to help - 864-907-6004.
Also, thanks for the tag Edward Neal
Dave
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Not trying to sound like an expert, but I have stayed at a Holiday Inn Express before. I've had that happen before and Dave is correct that it is a rich condition. To correct that, this is what I did, but I AM NOT RECOMMENDING THIS BE DONE CONTINUOSLY. I would short shift into the next higher gear WITHOUT lifting out of the throttle. Keeping the engine at the proper a/f and not having to cycle from wide open, to off throttle and back to w/o seems to work. BUT it does put a little extra strain on the transmission (although I haven't heard of any Slingshot standard transmission failures) and you have to make sure you're able to power shift fast enough to keep the rpm's off the rev limiter and not miss the shift. If you're not trying to get the most out of the performance, then shift as normal (keeping it off the rev limiter) and slowly roll into the throttle once the shift is complete so as to not flood the engine with the massive dose of fuel from these 63 lb injectors (or whichever ones you use with the stage I kit. Just a thought, but again DO SO AT YOUR OWN RISK if you choose option #1
