I'm still trying to tune the car in and lately I've started having lean issues. The target afr will be 15 say and the accel enrichment will stay rock solid and the pw will be stable but the AFR reading will start to creep up then climb to super lean (this is under constant throttle, like cruising or idling) hit 18 something or 22 something then start cycling between this high number and a number a point or so lower. I looked at the datalog and noticed that the tps reading usually hoppped right along with this cycle and the tps reading was negative(so it would be cycling between -2 through -4 and back say) even though I've zeroed out the TPS several times. Any clue if they are related and what the cause might be?
thanks
negative tps values and lean cycling
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
Re: negative tps values and lean cycling
Check the output of the TPS varies smoothly from approx 0-5 volts as you open the throttle. A scope can be useful to see this is a smooth transition with no spikes due to a worn/dirty track. If you can, check this at the DB37 connector. Also, how is the TPS grounded?
Dave P, London UK.
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Re: negative tps values and lean cycling
I'm also having problems with noise from the TPS and map sensor, I've seen a smooth response from the TPS, though it has noise. To compensate for the noise I've lowered the lag factor down to 20 which has stabilized it a good deal and the AE% threshold is at 10%. The return spring is very strong and I've tried a new TPS to fix the noise issue, but it didn't do anything so I took it off. The only thing I can think of that I did around the time this started up was I reduced my idle, by backing out the return stop then recalibrating the TPS, from 800ish down to 550ish. I've rechecked older msq save files and even gone back to one of them before this issue started, but the problem has persisted. The TPS is grounded to the TPS return on the relay board (btw I'm using a holley projection2d install).
thanks
thanks
Re: negative tps values and lean cycling
I think I solved my problem. I have a one wire powermaster alternator installed and called them regarding my somewhat erratic voltage readings and the tech suggested I ground the alternator housing to guard against a poor ground. I grounded the housing to the MS common ground on the engine and I've stopped having these related problems (so far at least).