What would cause engine missing, and make the tach and speedo bounce around at the same time??

I was sure it was the ICM, so I replaced it. Problem not solved, $150 gone.

I looked in the helms for what causes the engine to miss, but all the causes listed, besides the ICM, couldn't make all the problems I am having.

 

possibly the ignitor. could be the alternator going bad. what else is it doing if anything and when does it do it?

 

check you grounds?

(maybe?)

t..

 

Ok, I could try the ignitor. I heard a bad alternator could cause my tach bouncing, but I don't know how it would make the engine miss.

Very Rarely does the tach bounce around at idle. Idle seems smooth, but it did kill the other day while ideling. When I hit the gas at all, the tach seems to go crazy, and the engine misses.

 

On some of the older models (pre 89) the ecu does receive a power signal via the alternator, of course most components receive the same power source, but the ECM will be the first to respond and throw a code indicating ecm signal failure..

Is the car actually mis-firing? and is the tach in synch with the motor failing? I mean if the tach jumps up 250 rpm's you will hear a significant idle increase...

Ignitor controls tach and fuel injector circuits and may be worth considering...

 

The tach is not in synch with engine rpms when it jumps. I can be crusing at 30mph in 5th, and my tach reads 7500 rpms. Then it will go to normal, then bounce, and so on...

 

Ok... If the check engine light is not illuminated then I would expect a bad tachometer here... its not so easy to determine without a proper scan tool, but if the tach jumps while holding the gas pedal steady then the tach is outta whack...

 

I, like Tinkerbell suspect bad grounds here. Check the engine grounds, valve cover, battery to car to tranny, and the ground on the thermostat housing.

 

HAHAHA I know what this is!!!!!!!!!

Check your ground at the thermostat housing, and also check the resistance between the (-) battery terminal and the block. It should be less that 0.3 ohms anywhere on the block. If not, then you have a bad main ground from the tranny to the frame....





EDIT*** DOH, Ryan beat me again! Argh...............


[Modified by B18C-EJ1, 3:11 AM 8/14/2002]

 

You guys are the ****!! I will have to try what you said today!

Thanks.

One question, how do I check my grounds?? Just see if they are still connected?

 

With a DMM (Digital Mulit-Meter) or Volt - Ohm meter.

 

TTT.

HX, you fix it?

 

Well...I fixed it today. I was removing my 450cc injectors because they were sold, and I was going to check the grounds as well. The ground connecting by the thermostat was loose. I loosened it some more to see what that would do, and the fuel pump wouldn't even prime, and the check engine light was really dim.

So I tightend the nut, put the stock ecu and injectors back in and boom, its all good.

That loose ******* ground wire cost me $150, and not driving my car for like 2 weeks.

I am happy it is fixed though.

 

good old grounds - simple, yet such a notoriously problematic area...

glad its all better

t..

 

Thanks man, GROUNDS SUCK!!!

 

 

Dude its your distirbuter, I pretty sure because my dads old accord was doing that and so he replaced it and it fixed the problem, it jumps from like 1000-6000 then drops bck down right> yeah those are the same things that were happning to my dad. It took a while for him to figure out what was going on.

Blaze

 

I fixed it guys. It was a loose ground.

 

SWEET!!