: Engine Surge/Hesitate



CadillacKid07
05-16-05, 07:24 PM
Hi there, I own a 1997 Concours with ruffly 81,000 miles. Recently the engine has begun to surge. When accelerating the engine surges, but only when in gear. I have already replaced the fuel filter, fuel regulator, air filter, oil filter/change. Any ideas on what may be causing my car to do such a thing? Thank you for your help.

slk230mb
05-16-05, 07:57 PM
Do a search for cleaning the carbon out of the throttle body.

CadillacKid07
05-17-05, 11:48 PM
As far as I know, the throttle body is pretty clean. If looks are deceiving my eyes, then what would be the best way to remove the carbon build up from the throttle body. Also, I had a independant mechanic look at it, apprently the air screen is missing, and he believe's that the mass flow air sensor has gone bad as a result of the screen missing. Any idea if that could be part of the problem.
I had a thought of my own, could the problem be cause be either a faulty plug, wire, or coil pack? Would it be worth it just to have the general tune-up done to the car and then go from there? My biggest concern is getting the problem fixed so I can drive my car again; it would be in my better interests to spend the money on the problem first instead of the tune-up (unless that is the problem), then after the problem is fixed then get the tune. Any futher advice or thoughts on this matter would be greatly appreciated. Thank you and thank you slk230mb!

N0DIH
05-18-05, 01:03 PM
NEVER allow anyone to remove the MAF screen! It is a cruicial part of the MAF for proper operation. It also as a side benefit protects the MAF elements from debris that makes it past the air filter.

Check for the wires inside the MAF to be clean. Use a soft dry cloth and be very careful.

Typically a bad coil won't cause surging, it will cause bucking and backfiring. EGR can also cause surging problems. Typically it all comes back to a lean mixture. Coil is weak, doesn't fire, raw fuel is in exhaust, O2 sees not enough O2, pulls back fuel.

Take a look at my posts on the integrator and block learn. See what it is running. That might give you more a clue. Don't just arbitrarily replace parts. Diagnose it first.

CadillacKid07
05-18-05, 04:17 PM
Thank you Thank you Thank you! The biggest problem is that the screen is missing, and has been missing. So at the moment, I have the screen ordered and the new sensor. The parts that were replaced, were replaced for a reason, they deffinitly had gone bad. But thank you again for your help and I will keep you informed of my findings. And I will also read your previous posts to learn more. Thanks!

Ranger
05-18-05, 08:40 PM
The "screen" is actually an air flow straightener. As NoDiH said it is an integral part of the MAF sensor. I know it can cause drivability problems without it but I am not sure exactly what. I would wait til you replace the straightener and see if that solves your problem before you throw anymore parts at it.

cart69
05-19-05, 01:15 PM
i would look real close at the plugs and wires, my seville is a 94 with 89k miles on it and was missing and surging all the time, finally i put plugs in recently when i had the motor out but plugs are easy with the motor in the car!!, and i am waiting for the wires to come in, but the plugs were shot!! new plugs and now the car runs better than when i bought it!! NGK TR55 plugs

powerglide
05-20-05, 09:54 AM
I suspect a plug/wire/coil.

One of those. everytime I had your symptoms it was one of these.

Check you code, does it show P0300 Misfire?

Look here in the northstar section for 2 threads I started.

One's about doing a plug and wire change to fix the problem and the other is to easily see if one of your coils have gone bad. (The dealer charged me 350 bucks to do a coil replacement which I did for $28 in the auozone parking lot in 3 minutes)

eldorado1
05-20-05, 05:59 PM
The "screen" is actually an air flow straightener. As NoDiH said it is an integral part of the MAF sensor. I know it can cause drivability problems without it but I am not sure exactly what. I would wait til you replace the straightener and see if that solves your problem before you throw anymore parts at it.

Yep. Creates a laminar flow across the sensor..... Otherwise you'll experience the symptoms above - surging idle and hesitation, since the sensor won't know exactly how much air is moving past the sensor... typically though, you just see it run a bit rougher. I'd bet your problem will go away once it's replaced.