KADE bogging after highway drives, help!

[240ShaneX]

Hey guys, I have this really strange issue with my KADE. After driving at RPMs of 3000-3500 on highways for an hour plus, when I exit the high back to city streets the car bogs in every gear really bad. Mostly in 1st, its hard to get going, then it smooths out a little, but if I give it half throttle or try to go above 3000 RPMs it bogs again, but runs smooth at 2k-2500. This happens every time I come to a stop.

Now the strange thing is that if I let the car fully cool down, like over night, It runs fine if I stay driving around town. It revs like usual (fairly smoothly, has always had a slight hesitation in power above 5k) throughout the RPM range, and doesn't bog at all. I recently replaced the o-rings on all the injectors and the fuel filter. Also checked the spark plugs and they look good.

Anyone have any idea what might cause this issue after long drives at continuous midrange RPMs? Any ideas are greatly appreciated!!!

[4cefed]

(fairly smoothly, has always had a slight hesitation in power above 5k)

It's best to address things like that before they become larger problems. Now you might have the same problem that got worse or a new problem compounding the issue.

As far as the bogging, If you're sure of the fuel system, them I'm going to guess dirty MAFS, or plugged cat, leaning toward cat. If it's gone bad, heating up might make it worse and choke off more flow.

[240ShaneX]

thanks for the reply 4cefed. I thought I had addressed it when I replaced the injector o-rings, fuel filter, and sprayed a can of seafoam through the IACV. I didn't notice much of a problem until now. I have no cat, o2 sensor was replaced about a year ago. I have no CEL and I didn't want to just start ripping things apart at random and replacing them til I found the problem (which I hope I dont have to do now). It's just really weird that it really doesnt have a problem around town, and doesnt even have a problem on the highway UNTIL I slow down to city speeds.

MAFS has been cleaned several times so I don't think its that. I would think maybe the injectors might be somewhat clogged, or fuel pump weak maybe, but when it sits a while the problem goes away?? that just doesnt make any sense at all to me.

[4cefed]

My friend hand an Audi that did something like that. When the engine was warm it wouldn't want to start. I want to say it was related to the fuel pressure regulator.

When it bogs does the ignition break up or is it just no power? If it breaks up it might be a weak coil, a faulty MAFS, or even a bad temp sensor. Otherwise maybe the fuel pump is going. How do the electrical connectors to the fuel sending unit look? I wonder if you can borrow a fuel pressure gauge from somewhere and run it under the hood up to the cowl and on the windshield and drive around and see what the pressure is doing. I ran a permanent one on my CSX that was mounted outside, it came in handy a few times trying to figure out things like this.

[240ShaneX]

It was the fuel pump. I could hear it at startup and it sounded progressively worse, then I could hear it bubbling when I shut the car off, so obviously it wasnt holding pressure. Replaced it with a DeatschWerks DW200 pump and it runs MUCH better now. Revving is very smooth all the way to redline with no loss in power, starts are better, and power delivery is MUCH smoother and linear.

[4cefed]

Glad it's fixed.