91 348TS. When engine is warm. Idle surges, rpm up and down. Sometimes engine dies repeatedly when wam. Not sure if it is related. But they started happening around the same time. Any idea what might be the issue ? Thanks.
My goto on any weird idle/surging is an ECU reset. not kidding. I just unplug the battery, and redo the start sequence. I swear it's the change of seasons. If you have an idle air valve, maybe it's a little wonky. sjd
Curious, any issues when you do a hot restart? Does it strain to restart? Sent from my SM-G965U using Tapatalk
Certainly a reboot is always good! If it sounds like running on 7-8-7 at an idle, stalling when coming to a quick stop, then check the wiring plug connectors to the mafs'. Wiggle them around, if idle improves, then shut it down and reach for the contact cleaner. Those connectors are notorious for poor idle/stalling, as well as the idle/air valves.
The extact same thing's happened to mine, up & down sometimes at idle & cuts out & sharp stops, seems to fair better if I don't coast. I those aren't expensive things. The mrs doesn't want me spending anymore money on it for while after spending £3k on a clutch, handbrake & a lock repair.
A few posts on cutting off when stopping if you want to check them out. My car did those too. They pretty much ALL do as they age. Now mine drives like it was off the showroom but I went through it all with an inventory list and checked them off as I replaced. Nothing worse than a dream car as reliable as an MG you don't trust to drive. My opinion it is why they are bought with great glee and sold < 12 months later in annoyance, wash rinse repeat. So easy to fix as DIY no less. Straight remove and replace jobs. Order can vary and there are opinions on that but this is my suspect list generally assuming you have no CEL and the CEL lights both work. You can check resistance and voltage etc and not straight replace but it gets tricks with intermittent issues. I'd replace these to start, in that order, no engine code so your in remove and replace mode, sometimes its a combo. Crank sensors can mimic wiring issue or itself has frayed wires causing that cut off. Kia ones work but I used OEM Bosch ones $250 O2 sensors, get real ones from auto parts not from the Baltics at really cheap prices. $140 Cam position sensor. People say they fail suddenly, but they start to throw wonky singles intermittently before they fail that can go on for some time. $85 Still having issues after that FPR & Clean Injectors $125 (Bosch not available but Intermotor is adequate) Bosch Ignition modules $160 (xref to Porsche part numbers) Bosch Coils $100 (xref to Porsche part numbers) Still having issues after that Rebuild Bosch MAFs. You can't buy them, but you can rebuild them. They just plain wear out and do get water intrusion. (Personally I'd do that first) $500 Bosch Fuel pumps $250
Perhaps the first thing to check are the Idle Control Valves. They can get gummed-up and sticky. A good clean-up of the valves may solve the issue.
Here is an example I suspect not but good maintenance item to try and costs like $6. I did that on mine, despite them being clean. Still had issues. Assumed maybe spring tension was off. Eventually replaced them with new BOSCH IAC. For me it was a combination of things slightly off due to high time on the components.
I had a similar issue. I cleaned my MAFs and replaced the O2 sensor on the bank that was throwing a code (finally. For a while no code - just random issue here and there until I noticed every start up I had a rough idle that sorted itself after warming up)
One thing you can do also is balance the intakes with the air screws. Over time people monkey with those. You can use vacuum gauges, it is in the WSM, that smoothed my idle a bit too, actually it was the final thing I did. My rough/surging idle was a combination of things, unfortunately it is often not just one thing. The major contributor to my occasional cold idle was a failing MAF, no code just not reading like it should after 30 years. Replaced them both with new ones. Once that was solved among other things, loose fuel line on the tank fuel pump for example, balancing the intakes really cleaned up the idle as banks were not "fighting" each other anymore. Purrs like a kitten now with no bobble or blurb when cold or warm when idling any more. Like a sewing machine, very nice.
