01bluecls

I have 51k Miles on the odometer, transmission replaced at 36k. Comptech headers and icebox installed around 48k. Recently in the past month I have noticed more and more Im getting some shuddering vibration upon exceleration in the midrange rpms. When I give the gas half throttle it seems the car starts to shake as it accelerates. When i let off the gas, the shuddering goes away so I know it not the suspenstion or wheel balancing.

Just Yesterday when I have 4 people in my car for the first time, the shuddering during acceleration was worse, im thinking because of the added people/weight the engine was working a little harder of course. I checked the air filter and its pretty clean. I use the same 93 octane that I have been using for the last 2 years.

I wanted to see if anyone else is getting this or might know what it is. I know it could be a lot from Throttle body being too dirty ( I have never checked or clenaed it ever), maybe dirty fuel injectors, maybe bad spark plugs.....etc. These are all just my opinions of possible causes. Any advice is appreciated. Im out of Acura's warranty so taking it to the dealer for free isnt a solution.

01bluecls

Forgot to mention i havent had any CEL's or anything of the like happen since I have owned the car after 36k.

dshearon

iTrader: (1)

i had the same thing happen around 56K... i changed the spark plugs and it went away..... not sure if that is your problem though.... by the way i thought the standard acura warranty was 60K dont you have 9K left?

01bluecls

Acura's warranty is 4 years or 50K from original date of purchase. I guess I could upgrade to NGK spark plugs first to see if that is the cause. Anyone else have any suggestions??

Chemmech

I had a similar problem, then my transmission went out the next week.

6MTpromises

could be motor mounts...have it checked out

bojangling

I think I am having the same problem. No idea what it is or what to do. If you figure it out, let me know.

CALscuba

I was having a similar engine vibrations on my CL-S when the engine was under light load. Engine shakes when giving it gas gently to drive up a hill at freeway speed in traffic. (Not WOT on a stretch)... For someone who is tuned to his card it is easy to discriminate between engine vibrations and road bumps, tire balance, wheel alignment.

I took my car to the dealer. The master tech told me he could see misfirings from the OBDII freeze data. But that is all he did besides sending me home with a disconnected vacum line to the fuel pressure regulator

The Hitachi CM11-107 over-head coils seem to be getting gradually worse.
I started gaping down my plugs from 1.05mm to .80mm now. I got instant relief, much better pick up, less freeway engine vibrations and less engine noise.

Remember that the 3.2L type S engines have a higher compression ratio and run on lean mixtures for "UltraLowEmissions" label. What that means is it is much harder to get a spark under these conditions than with a run of the mill engine. I recall my Honda motorcycle days when plugs where gaped at .65mm to .70 with similar 10-to-1 compression ratios.

I did switch to Denso Iridium plugs IK20 (similar to TL'05). Well these plugs helped just a tiny bit but the .8mm gap is what helped the most not the .4mm center irridium electrode vs the stock double platinum. I can not count how many times I have taken the plugs out to regap (Use antisease compound to spare the head threads)

I am still testing to get to the final solution... but I can say everything points to a weak spark from the overhead coils (45KMi only). I could not find a definit trace of "coil epidemic" on forums or TSB's. Besides the same Hitachi coils part No is still in use in TL'05 and Accord'03... For all I know Honda engineers must be happy with them and the dealer tech says he has not heard about these coils getting gradually weak (internal short?). The dealer guy at the part counter says the same: the coil inventory is not moving I can not discount that dealer personel was trained to keep this type of info confidential.

Perhaps back in 2001 Hitachi made a bad batch of coils? These coils are directly exposed to the high engine heat. I can see how coil wire insulation may have a tendency to weaken and let the spark jump between windings.

If you want to do some home work for instant results:
gap your plugs all equaly between .7 and .8
Charge your battery to max with a charger.
While testing don't use any juice (AC, headlights, stereo) to keep the battery voltage as high as possible. These coils are really touchy with primary voltage *
(*)Yes my alternator does put out 14.5 under load)

Upon starting, memories of the first 5kMi of your engine will come back:
Distinctive low and loud pitch at idle
Great low rpm torque due to cyclinders being balanced
Quicker smooth pick-up due to richer mixture from happy O2/ECM
Engine starts faster with less crank time due to narrow gap
quicker gear shift in automatic mode due to more torque available
No decrease of performance in 3rd gear on the freeway!

I am going to swap all 6 coils to get to the bottom of this issue... Let me know what your fiding are in the mean time

Has any field tech dealt with weak sparks on these Honda coil-over-head motors?
-Sam.

civicking

soudns like a bad trans, sounds like its slipping, how many miles do you have because acura offered a 7 year 100,000 mile warranty on the trans.

MotionEffects

I bet you have the Same problem as me. Does your car Shake side to side when acceleration, usually on top of second gear and third. Couple of members have that problem and Im having it as well. My buddy at Honda said its the CV joint, but another member on the board said he got his Halfshaft replace. But those are the predominant causes of Side to side shaking when under load.

CALscuba

It seems like half-shafts failure cause the engine/trainy to shake side to side where weak ignition coils shake the engine front to back (transversal engine).
That should make it easier to isolate the problem.
Besides shafts will have increased free play that will likely make an audible noise.

To test the shafts in an empty parking lot: steer the wheels out all the way left or right like you are making a hard turn. You need to extend the shaft on the side you think is bad. If you ear a clunk noise on pick up there you have it.
My shafts being okay I keep my fingers crossed and I stay away from lowering my front suspensions because that puts stress on the shafts by no longer working in a straight line from trainy to hub.

Today I drove 40 Mi with my "tuned ignition"... boy, what a huge improvement


- Engine has a much greater torque (ie low rpm power).
- The ECM/ECU computer is able to up shift gears at a lower rpm.
- Controlling the throttle is much easier because you get power right off from idle.
- The pedal is more responsive to the point it is now touchy.
- It is easier to get the car cruising at low speed in traffic.
- Breaks are stronger because the EGR is less involved, higher B.booster vacuum
- Above 5,000 rpm the engine puts out power and remains quiet besides the sweet vtec transition sound


Before this ignition mod I always had to drive in mid rpm (3 to 4K rpm) to get some power. Now the power is there but I hardly have go past 2,500 rpm to get it. The engine torque is back!

If you believe that a high spark plug gap gets you a stronger spark, think again. In fact in our case it's quite the opposite. That is what testing shows.
With the stock gap between 1.0 and 1.10 you get a lot of misfiring and unburned gas. Both O2 sensors mounted on the exhaust collector cause the ECM to lean out the mixture and decrease the amount of gas injected to both front + rear banks: you get less juice to keep emissions low! The bottom line is our weak ignition coils require lower spark plug gap.

Since I own both a 32CL-S and a TL'05, I can do further coil testing with the TL. TL'05 uses the exact same coils and seems to have the same weak spark problem.
Overall I am not a fan of narrow spark plug gap but this helps point out the weak ignition spark problem. We can clearly see what power we are missing

At this stage I don't have a long term solution yet. Ideally I would swap the coils for MSD replacements but MSD does not have an application for our 3.2CL-S engine. Our coils integrate the control logic for the coil (+12V, GND, Trigger). I can't find a compatible performance aftermarket part.

The BIG DEAL : if these Hitachi ignition coils go bad this could mean a huge recall for Honda because they are used on many-many engines (Accord V6'03, TL'05, 32CL's, 32TL's and newer 4 Cyl ...)

If these coils are simply weak since day one then we're screwed If that is the case I have "plan-B" on the bench to live with these coils.

Go ahead pull out your spark plug wrench, gap your plugs to 0.8mm! Enjoy your engine torque and the gas $aving$ then report... I can write a help procedure for those unfamiliar with S.plug handling.
-Sam.

kensukikatayo

My friends 2000 Subaru 2.5RS Coupe was having the same problem (shuddering when accelerating at high speeds) and then his Check Engine Light came on. He just changed the spark plugs and now his car's fine.

phipark

I have the exact same problem. I guess I'll try to change the plugs and see what's going on. The dealer checked my CV joints and says everything is fine there.

brianmac64

Did you ever end up swapping the coils out Sam? I'm debating re-gapping my plugs after reading this.

phipark

I just replaced my plugs this weekend and the shuddering is still there. I got the IK20 gapped to .9 mm. Back to the drawing board.

moomaster_99

Its probably your CV joints/Half shafts...one in the same.

01bluecls

THat's exactly what it was. THe dealer replaced the drivers side and when I got the car back with the same problem. THen they replaced the passenger's side and wah lah...problem solved. All of course covered under my extended warrant!

kensukikatayo

I had the extended warranty too... but the first owner cancelled it but at least I got my SRS light fixed under that warranty cuz the dealer didn't realize it was cancelled.

03CoupeV6

I have a TL-P that shudders right after changing into 2nd gear. Transmission, you think? It feels a lot like what's been described on here which is why I posted this.

phipark

That's what I have as well. I think I'll have to drive my car with the mechanic in it and/or take it to another dealer.

2JZGTE

Same problem here , shuddering when accelerating at high speed.
'01 TL-P, ~127,000 miles. Didn't think so many people had this problem as well.