"check engine" with Accord - B20A1 engine

[Lok]

Dear 3geez friends, I would like to have your help in a recent issue I have with my car.

Actually I bought recently (my second) 3rd generation Accord (with B20A1 engine).

The check engine light comes on every time I drive the car. Nothing weird really happens; just the check engine light comes on.

I checked with the Honda electrician all the connections and they are look fine.

ECU self diagnosis return 12 Led blinks? Technician told me that according to his book is problem with the EGR valve? But this engine hasn’t got any EGR system? It has only an air valve.

We check also the vacuum hoses and they are fine except that 1 unit “air filter” in the black box is completely missing.
Is possible that this missing unit cause the “check engine”?
By checking Honda manual, look like this unit is not connected with the ECU?

Also another problem I experience is that when the engine is warm, between 1000-2200 rpm the acceleration is a bit erratic, you feel that the engine is not working properly. This happens only when the engine is warm. After 2200 rpm the car accelerate very smoothly under all conditions. I don’t know if this has to do with the “check engine”?

And 1 last, if I drive the car 1 day for many miles (let’s say 160 miles), sometimes the tachometer starting doing crazy thinks. The engine is working smooth. Only the tachometer gets crazy. Next day everything is working fine!!??

Any input or similar experiences (with the above) from your side? will much appreciate it.

[2oodoor]

My first thought is your driveabity symptoms seem distributer related. I would do a good check up on that part and also check igintion timing. The "on board diagnostic" of this generation honda is unreliable at best because the sensor inputs are somewhat daisy chained, meaning the sensor output really is misleading because one sensor relies on the next one being accurate. It could be coolant temp reading up at the throttle area, is out of range for example. That could be a dirty sensor, air in the coolant system, connection, grounds or a bad component.
You need to use the EDM diagnostic flow chart for this car, are you sure it is not a B20A2?
It is a good chance the CEL and the driveability issues are not related, always keep that in mind

[Lok]

Many thanks for your valuable input.

I thought the same, maybe the igniter unit in the distributor cause the hesitation in low rpm and the tacho jumping.

Yes, is a B20A1 engine. Originally the car has B20A2 engine, but for some unknown reason to me, previous owner change the engine to B20A1.

I have checked Accord manual but the vacuum diagram and is a bit different and is referring only to B20A2 engine. You can understand this, easy, by the 2 vacuum tubes going on throttle body. On B20A1 there is only 1 vacuum tube going on throttle body.

I was lucky enough to found the vacuum diagram of B20A1 engine on 2gen Prelude manual. Now everything is perfect connected except (as I told before) to the “air filter” unit on black box, completely missing..

As you advice, I will try to clean all sensors, check all the connection again but I may learn to drive this car with the “check engine” light on….:-)

[AccordB20A]

my best guess is if its flashing 12 times its looking for an egr valve thats not there. the b20a2 must have had one and the new b20a1 does not.

[AccordB20A]

and the hesitation and tach problems will be related to the distributor. when they get hot they fail so the ignitor modules on its way out.

[Lok]

my best guess is if its flashing 12 times its looking for an egr valve thats not there. the b20a2 must have had one and the new b20a1 does not.

The funny think, is that checking the 1987 B20A2 Accord manual, did not have either an EGR valve. But also the manual does not give any ECU 12 Led blinks indication. It gives only 11 and 13 led blinks. It has a note only that if you get 12 blinks check the ECU?!! Is total confusion.. But anyway the car is very nice, and accelerates very strong, apart the hesitation up to 2000rpm..

[Lok]

and the hesitation and tach problems will be related to the distributor. when they get hot they fail so the ignitor modules on its way out.

Many thanks for your advice. Yes, when you drive around town, let's say for 20 miles, is working nice. When you travel for 100 miles+ the tacho is starting jumping around.. The hesitation at low rpm is present as far as the engine temperature comes to normal.

I'll try to find one ignitor module, as is easy (a lot of Honda models share the same unit), and see if will clear the defect. Is quite hard to find a distributor unit in my Country for that engine.

Many thanks again.