Engine Hesitates and Jerks
 

I have a stock 99 Protege ES with the 1.8L engine. Lately it's been hesitating and jerking intermittently. I've had the fuel system cleaned but that did not solve the problem. The problem seems to be quite random as to when it happens. The shop I took it to said the computer threw a code indicating an air flow problem (EGR valve I think they said) but they didn't feel this was the problem. Has anyone else experienced this problem? I see from the alldata.com site that there is a TSB 0500499 dated May 99 that indicates "Engine - Intermittently Hesitates or Jerks" but I can't view the details of the TSB. I've also had the ignition coils replaced under the recent recall notice.

Any tips or suggestions would be greatly appreciated. Thanks.

I doubt this is your problem but here is the TSB.....

VEHICLE INTERMITTENTLY HESITATES OR JERKS

APPLICABLE MODEL(S)/VINS
All 1999 Protege with manual transmissions (M/T).

DESCRIPTION


The vehicle may intermittently hesitate or jerk when accelerating or just before shifting. This may be caused by the customer resting their foot on the clutch pedal and unknowingly or prematurely depressing it enough to close the clutch switch. This action sends a ground signal to the PCM which causes a fuel cut and timing retard condition.

My car also gave a EGR Flow code once which I think is due to the Intake Manifold being very dirty and clogging one of the EGR prots with carbon. I still have yet to have cleaned out. You may want to check your throttle body and intake manifold a with a flash light and see if it has a carbon bulid up.

Hope this helps.

You're right, this isn't it. I don't ride the clutch and the hesitation and jerkiness happens at idle and while cruising. Also I just spent $150 to get the fuel system cleaned out. However, I'll check the intake manifold and throttle body as you suggested.

Maybe there is a problem with my clutch switch or PCM. Something else to check.

Thanks for the info.

Is your check engine light on? I was wondering if they found that EGR code without it being on? My light was on when the dealership found the code PO402 on mine, and they said nothing was wrong. But I guess the light just gave up and decided to turn off and has been off for several months now. I am hearing spark knock now and I notice idle drops sometimes right after start-up, but the car runs great out on the road.

Yes, the CEL is on. The shop that worked on my car reset it twice already but it keeps coming back on with the same code. I found another thread that mentioned a problem with the O2 sensor. Maybe I'll give that a try.

Do you have a cold air intake cause mine started doing that too. If so I think its because our ecu are sensitive. I've been told an air/fuel controller can fool the ecu to working properly. I haven't tried it yet saving up money to do that.

My Protege is strictly stock at this time. It's got whatever it had coming out of the factory.

TheMan,

The code the computer is throwing is P0401 "Exhaust Gas Recirculation Flow Insufficient Detected" but I'll check out the EGR valve and the vacuum lines. Where would I find the EGR valve and what's a good way to test it? Thanks for the help.

Hey,
I have had the same problem with my car. I also have a 99 pro es, stick. It also does it randomly we can say maybe once every 3 weeks and it lasts for about 4 days and it dissappears by itself. I have ngk wires, air filter but I don't think that this would cause this. How many miles do you have in your car.

I have just over 70k on my car. I recently installed new wires, plugs and air filter myself. Does your CEL come on? If so, do you know what code the computer is throwing?

Did you have your coil packs changed under the recall yet?

Yep. I was hoping that was the problem but it wasn't. The dealership didn't even comment on the car running rough. Of course I've never received very good service from my local dealer.

I have 22k on mine and the dealership told me that nothing was wrong i just need to put my stock air box back in. . I said my car is hesitating on accerating from a stop and jerks sometimes. Sometimes makes a popping noise when going from a stop. The code came up as po172 (adaptice fuel control) pcm unable to control fuel and emissions with aftermarket accessories. Which is my Injen cold air intake.

Well I also have about 78000 miles and it started since I got to 70,000. I went to the Mazda dealership and I told the guy that my car jerked when I was going around 45milesper hour and I was in 4th gear and he just told me to switch to 5th but I has kept doing the same thing. It also jerks sometime when I trie to accelerate like if I'm going 15miles per hour in 3rd and I decide to floor it it jerks, it really bothers me. Have you changed your timming belt, I haven't and I know that I have to do it soon, maybe that could be a problem. I'm going to get another opinion from another mechanic this week and I will keep you posted. Post any info you receive. Thanks

Thanks for the info. It sounds like we have pretty much the same problem. I haven't changed my timing belt yet but if that was it I'd think the engine would be running rough all the time. That's the weird part. If it was something that was broken you'd think the car would be acting up all the time. Maybe there is a vacuum leak somewhere as TheMan suggested. I would appreciate hearing what your second opinion has to say.