engine problems '88

[CRXJerk]

So i have an 88 CRX. Just had the valves done and i'm still getting oil on my plugs. The exhaust kinda smells funny but has no visible colour or smoke. The idle will go from 750 to 2000 rpm then repeat in a continuous cycle. Plus as the weather warms up it's getting harder and harder to start. There is no oil in the coolant and no coolant in the oil so i don't think the head gasket is gone. Any ideas?

[Kegger]

Is the oil on the firing end of the plug or not?

Idle problem is cuz of your idle air control valve on the back of your intake manifold.

Test your battery.

[CRXJerk]

Battery seems fine, and the oil is on the piston side of the plug :S the valve cover gasket is fine. Valve seal were just done about 4 months ago thinking that that was the problem. I'm thinking piston rings but then wouldn't the little bastard smoke all the time? The engine exhaust does smell kinda weird but there are no visible colours.

 

I found this in another forum:

How the idle speed is controlled

 

The idle speed is controlled by three methods:

 

The cold idle value, which is located under the throttle plate. Late model engines may not have the cold idle valve. The valve consists of a air channel bypassing the throttle plate which is blocked once coolant heats up a wax element. When the engine is cold the cold idle valve will allow a lot of air to bypass the throttle plate, and the idle will be around 2000 rpm. As the coolant warms up the cold idle valve will slowly close, bringing the idle speed down.

The idle air control valve (IAC or EACV), which is located on the back of the intake manifold. The IAC valve is a solenoid which is controlled by the ECU using pulse width modulation. Thus the ECU can control how far the solenoid is open and how much air bypasses the throttle plate. There are limits, both upper and lower, to the amount of air which passes through the valve because the solenoid will only work from 20% to 80% duty cycle.

The throttle air bypass screw, which is located in the top of the throttle body. Unscrewing this will allow more air to bypass the throttle plate, and so will increase the idle speed. The purpose of the bypass screw is to adjust the amount of air going pass the throttle plate so that the IAC valve duty cycle is within the limits of what the ECU can control. The manual tells you how to adjust this screw by unplugging the IAC valve.

TPS adjustment

 

The TPS tells the ECU what position the throttle is in. The TPS should read 0.45V when the throttle is released. It is critical that the TPS is adjusted correctly so that the ECU knows when the throttle is released, which tells the ECU that the engine is either idling, or the throttle is closed under load and the injectors should be switch off the save fuel (fuel over-run cutoff).

 

If the TPS is set negative (below 0.45V at idle) when you open the throttle slightly the ECU will think the throttle is not open, apply the fuel over-run routines and cut fuel at 1400 or 1800 rpm. This will often cause the revs to cycle between about 800 and 1800 rpm. Also the car will be jerky when driving around at low speed.

 

If the TPS is set positive (over 0.45V) then the fuel over-run routines won't work, and also the ECU will not run the correct idle routines to keep the idle steady. It's better to have the TPS adjusted slightly negative, but setting it to 0% if fairly easy with datalogging. Otherwise aim for 0.45V.

 

Effect of mixture and timing

 

Normally at idle the ECU will run in closed loop, so the mixture will vary around 14.7:1 Running in open loop and enriching the mixture to about 14:1 increases the idle speed.

 

The stock setting is slightly retarded at idle. Adding 3-4 degrees ignition advance in the idle portion of the ignition tables increases the idle speed.

 

Idle problems and oscillation

 

The ECU has a 'target idle speed', which varies with coolant temperature and electrical load. When fully warm the target idle speed is 700 or 750 rpm. If the engine speed is different from the target idle the ECU will alter the duty cycle of the IAC valve to compensate. A combination of a duty cycle lookup table, the current duty cycle and the difference in idle speed is used to calculated the duty cycle for the IAC valve.

 

This is a closed feedback loop, and is dependent on the characteristics of the engine matching what the ECU has been programmed to expect. If any of the components in the feedback loop, or a combination of components are different from what the ECU expects, then the feedback loop fails apart and the idle will often oscillate. Don't confuse this with the oscillation which can happen if the TPS is out of adjustment and the over-run cutoff is operating. The idle oscillation is a good example of a lorenz attractor in non linear dynamics if anyone is interested is chaos.

 

For an example consider that the engine is idling at 750 rpm by using a duty cycle of 25% for the IAC valve. The engine speed drops to 725 rpm, the ECU calculates the difference of 25 rpm and calculates a new duty cycle. The tables in the ECU tell it that when the IAC is at 25% duty cycle and the idle is 25 rpm low, use 30% as the new duty cycle. This valve has been set by Honda as the correct duty cycle for the stock engine, and will return the idle speed to 750 rpm for a standard engine. If the engine has been modified it might be possible that the IAC duty cycle needs to be 50% in order to increase the idle speed again. Because the IAC duty cycle is too low, the idle speed drops, and eventually the ECU will give the engine a shot of fuel and open the IAC right up so that the engine does not stall. This will raise the engine speed to 1000 rpm or so, and the cycle continues.

 

The solution is to alter the behaviour of the idle speed components so the system is stable again. Usually adjusting the TPS, idle bypass valve, mixture and ignition will cure an unstable idle.

 

 

Now I'm not sure if these TPS voltage numbers are right for my 88 SI. Does anyone know how to test the IAC valve and TPS in an 88 SI?

[crxtacy]

if you have oil on the piston side then either the valve seal or the piston rings are worn !

i'd check the valve guide seals see if there seated right .

[VtecRex]

The idling problem could be caused by a vacuum leak at the intake manifold, injectors, or head gasket. Also if Honda is low on coolant it will do the same. The oil on the piston side of the plugs is caused by either bad rings or valve seals as some one else stated.

[crxtacy]

the only way to find out if its the rings or the guides is a leak down test .If you just had head work done then its prolly the rings.But i'd still do the leak down or a compression test.

I just had motor work done myself.My symptoms was hard starting when engine warm and rough idling.

did the leak down and sure enough the it was my rings.# 3 cyl. leaked .hear it through the pcv valve port.

At this time now ,don't know what engine to put in .Either way it will be a $$$ issue !

Hope your motor is still good dude !

[jasoninarmy]

im not sure about hondas, but on fords you can unplug the TPS and test it with a multimeter. if yours is a three wire setup u should be able to do the same.

 

 

anyone know which engine comes in the 89 integra rs?