Exhaust - System Buzz
Bulletin No.94-041
Issue Date
MAY 13, 1996
Model [NEW]
1994-96
ACCORD
4-CYLINDER
Applicable To [NEW]
See VEHICLES
AFFECTED
File Under
Engine
Exhaust System Buzz at 1,800 rpm
(Supersedes 94-041, dated November 28, 1994)
SYMPTOM [NEW]
A buzzing noise is heard at 1,800 rpm when accelerating at part throttle. This noise may be heard in cars equipped with either a manual transmission or an automatic transmission (see GENERAL INFORMATION).
PROBABLE CAUSE
Exhaust system resonance. [NEW]
VEHICLES AFFECTED [NEW]
1994-95 Accord: All
1996 Accord:
4-door - Thru VIN 1HGCD5 ..... TA170937
2-door - Thru VIN 1HGCD7 ..... TA019581
Wagon - Thru VIN 1HGCE1 ..... TA005776
GENERAL INFORMATION
Investigation has discovered two similar, but distinct, exhaust system noises: a buzz at 1,800 rpm, and a groan or drone at 2,000-2,400 rpm.
1,800 rpm buzz - This noise - a sound like a vibrating sheet metal piece - is most common in cars with manual transmissions (although it can also occur in cars with automatic transmissions). It can be reproduced most reliably by upshifting from first to second gear at a low speed (so the engine speed is approximately 1,200 rpm) and applying heavy throttle. The noise can be heard as the engine passes through the 1,800 - 2,000 rpm range. It cannot be reproduced by holding the engine at 1,800 rpm in neutral or any other gear.
Use the parts and procedures in this service bulletin to repair this problem.
2,000 rpm groan - This noise is most common in cars with automatic transmissions. It can be reproduced by driving the car in D3 or D4 in the 2,000-2,400 rpm range with a steady throttle. It is most noticeable when driving up a slight grade or in stop-and-go traffic. More sensitive owners may also feel a slight vibration in the steering wheel, accelerator pedal, or floorpan.
The parts and procedures in this service bulletin will have very little effect on this noise. Any noises in the 1,800 - 2,400 rpm range that remain after installation of this kit should be considered characteristic of the vehicle.
Other possible causes - Bent or misaligned components in the exhaust system can cause noises at various engine speeds. Diagnose this by examining the rubber exhaust system hangers. A problem is indicated by one or more of them being twisted. Correct this by loosening all the bolts in the exhaust system so the system can seek its own "neutral point." Then retighten the bolts.
CORRECTIVE ACTION
Replace the gaskets (see PARTS INFORMATION) at both ends of the mid-pipe. Use new mounting hardware.
1. Remove the four bolts mounting the mid-pipe to the catalytic converter and exhaust pipe A.
NOTE:
Some models have the heated oxygen sensor mounted in the mid-pipe. Do not damage it while doing this repair.
2. Remove and discard the old gaskets.
3. Install the new gaskets.
4. Reinstall the mid-pipe to the catalytic converter and exhaust pipe A with the new bolts, nuts, and springs from the kit. Torque all four nuts to 22 N.m (16 lb-ft).
5. Examine the exhaust pipe hangers; make sure they are sitting vertically.
PARTS INFORMATION
Exhaust mid-pipe fastener kit:
P/N 18010-SV4-305, H/C 5027362 (Kit contains two gaskets, four flange bolts, four springs, and four self-locking nuts.)
WARRANTY CLAIM INFORMATION
In warranty: The normal warranty applies.
Out of warranty: Any repair performed after warranty expiration may be eligible for goodwill consideration by the District Service Manager or your Zone Office. You must request consideration, and get a decision, before starting work.
Operation number: 311102
Flat rate time: 0.6 hour
Failed part: P/N 18229-SV4-003
H/C 4646386
Defect code: 042
Contention code: B07
Template ID: 94-0141A [NEW]