Help needed with multiple problems !

[laserwitpsi]

I own a 90 plymouth laser RS. I haven't had any problems with it until I went to start it up after driving the previous night. I started it and it began to idle rough and almost die. I drove it but it had no power and would die at a stop sign. The car has been running 12 lbs. of boost for the past 6 months and running great. I parked the car and went to start it the following day and it wouldn't start. I checked the battery and had it load tested it was perfect. I cleaned the battery posts and it still didn't start. I checked the spark with a screwdriver and it had spark. I swapped the ECU out with one from my brothers running 90 turbo charged Mitsubishi Eclipse and it still didn't start. I pulled the timing belt cover off and it appeared to be still in time by just looking at the top two cam gear marks. The timing belt had just been replaced 10K miles ago. I checked all the fuses in the engine compartment and they were fine. I next pulled the spark plugs out and they were all fouled out (covered in gas). I replaced the plugs with NGK BPR7ES and the car started but ran really rough. I was wondering if anyone has had this problem before and if there are any suggestions of what I should do next. Any help will be greatly appreciated, thanks.

 

[hereitcomes]

check anythinig with the fuel setup? No starts are also incorporated with a fuel pump. try that out.

 

[bmxer08NC]

I have a similar problem, mine isnt turbo, but it sounds like the same problem. I have looked around and it seems like this is a common problem with 1st generations. I am having the problem looked at by a DSM dealer on monday. I think that it is the ISC(Idle speed control) sensor or the TPS. This is all in theory of coarse until the problem is solved but you should probably use a voltmeter and test out both sensors. And if these are not the problem, then atleast you have ruled out 2 very big possibilities.

 

[oldman]

Did you make sure the crank pulley was on TDC when you lined up the cam marks? Did you check every cylinder for spark or just one? If you're sure you have both fuel and spark, compression test would be my next step.

 

[ddavisaf]

Sounds like you may have a dying coil pack or bad plug wires also. Ohm them out, then move to compression.

 

[realhp=turbo]

Ive had problems with my timing components mysteriously come and go. My advice would be check the CAS if theres oil around it or the valve cover is leaking you could be having a problem there. Also check the power transistor and go through the procedure of ohm testing the coil packs. Fuel fouled plugs and rough running on new plugs sounds like your not getting a hot enough spark. Id start there.
mike

upon further thought I would also look at the fuel pressure regulater (have it tested? )

 

[laserwitpsi]

I made sure the crank pulley was lined up with the two marks on the cam gears, I have recently checked compression it was 148, 150, 155, 160. I checked all four wires for spark but the car is still running rough. Could the problem be a sensor ? Camshaft position sensor ?

 

[laserwitpsi]

Sounds like you may have a dying coil pack or bad plug wires also. Ohm them out, then move to compression.

The wires are new and the compression is good. Could the coil pack be going out for over a month now and not die yet. The car still starts and runs rough.

 

[ddavisaf]

Yep. Just because something is new though, doesn't mean it's perfect. Test the plug wires anyway.

 

[ICGerms]

...The car still starts and runs rough.

Do a boost leak test. Check to make sure that your MAS is plugged in.

 

[laserwitpsi]

I did a boost leak test and found a few leaks but none that solved the problem, however there is a little leak coming from the back of the intake manifold where the throttle cable connects to the throttle body. The MAS is plugged in.

 

[steve]

ECT or O2 sensor anyone?
Could you find a datalogger and log:
RPM TPS O2-R ISC MAFS KNCK INJP COOL AIRT FTRL FTO2

That would help.

Steve

 

[GST with PSI]

ECT or O2 sensor anyone?
Could you find a datalogger and log:
RPM TPS O2-R ISC MAFS KNCK INJP COOL AIRT FTRL FTO2

That would help.

Steve

laser with psi is my brother (as you can see he so origionally came up with a user name.)

i have a logger i'll hook up to his car but my question is when logging the parameters you listed above, what would be some optimal readings for a stock 1g gst. in otherwords, what am i looking for as far as numbers go on my logger?

could this be a cam angle sensor problem?

other bits of information about his car:
-his base timing with the computer disabled was 5 degrees btdc

-the fuel pump appears to be ok. it kicks on and is heard audibly when supplied with 12v via the test connector on th firewall.

-the ecu was switched with mine which functions in my car (same model and year) perfectly.

-plugs foul easily to the point where the car will no longer start and smell like gas after being pulled. what would make the car run so rich? the mas has not been modded.

-could the fpr be faulty?

 

[spyder97gs]

Coil packs don't usually go out at once. More times than not they give you plenty of warning before causing ferocious bucking.

 

[steve]

i have a logger i'll hook up to his car but my question is when logging the parameters you listed above, what would be some optimal readings for a stock 1g gst. in otherwords, what am i looking for as far as numbers go on my logger?

The first thing we are looking for is the the coolant and air temp sensors are reading something close to the outside temp when the engine is cold.

That the O2 voltage starts rising shortly after starting the car along with the coolant temp.
Since it's a '90 it takes a while before the ECU will try to go closed loop. Somewhere around 106F the O2 voltage should start swinging between .7v and .4v (91+ cars do this around 86F)

The TPS should read about 10% at idle.
The ISC will start at 120 and drop to zero shortly after starting. As the car warms up it will rise and should settle betwen 10 to 20 when the car is fully warmed up. If the stays at 0 or rises much higher than 20 the ISC/ISCdrivers/BISS are bad or misadjusted.
FTRL (Fuel trim low) will give us some idea how well the ECU is doing with it's calculated fuel vs feedback from the O2 sensor. This can give some idea about the health of the O2, possible problems with boost/vacuum leaks, bad fuel pressure and a bunch of other things.
FTO2 is the realtime fuel trim feedback from the O2 sensor. Overtime this is averaged into the Low Mid and High fuel trims. It should track with the O2 sensor as the ECU dithers the fuel in closed loop.

Steve

 

[ICGerms]

Coil packs don't usually go out at once. More times than not they give you plenty of warning before causing ferocious bucking.

That might be true for 2Gs, but it's wrong for 1Gs. Mine ran perfectly one day and then later that same day the coil pack was gone.

 

[spyder97gs]

That might be true for 2Gs, but it's wrong for 1Gs. Mine ran perfectly one day and then later that same day the coil pack was gone.

Hence "More times than not." I understand it can happen, it's just more common for the to show some signs ahead of time.

 

[GST with PSI]

FTRL (Fuel trim low) will give us some idea how well the ECU is doing with it's calculated fuel vs feedback from the O2 sensor. This can give some idea about the health of the O2, possible problems with boost/vacuum leaks, bad fuel pressure and a bunch of other things.
FTO2 is the realtime fuel trim feedback from the O2 sensor. Overtime this is averaged into the Low Mid and High fuel trims. It should track with the O2 sensor as the ECU dithers the fuel in closed loop.

Steve[/QUOTE]

THANKS steve for the info. a few questions:

please correct me if i'm wrong but closed loop is begun when you vehicle uses actual readings from the oxygen sensor to calculate fuel curves. however this can only occur when the o2 sensor is hot and can accurately calculate oxygen values in the exhaust stream? this is the reason the computer needs an open loop mode giving the o2 sensor a chance to heat up.

is it also true the computer during open loop mode uses information stored as ROM in the ecu to calculate fuel curves until it can receive feedback from the hot 02? if during closed loop the computer uses a base setting how can the fuel curve be adjusted before closed loop operation occurs? i guess what I'm asking is what gives the computer feedback about how rich or lean your car is running if the o2 sensor is not. i would think you car would run like complete crap before closed loop is reached, but when it's cold i can't tell that big of a difference in my car's performance.

also:
-what would differences in low mid and high fuel trim percentages indicate.
-what is a good percentage to be at for low mid and high? i was told 100% was optimal?
-FTO2 is the average of low mid and high fuel trim readings?
-do fuel trim percentages indicate how rich or lean you car is running over a certain amount of time?
-over what amount of time are the percentages calculated?

sorry for all the questions but nobody has really been able to explain the values to me until now.

thanks again steve.

 

[oldman]

http://www.3si.org/plhelp/index.html

 

[steve]

Try looking through this to start. http://members.shaw.ca/costall/ECUprimer/index.html
Getting your hands on the 1G tech manual is also a great reference.

Steve

 

[GST with PSI]

this is what i could understand about DSM ECU operation. someone please correct me if i am wrong (and i probably am).

-la de da driving along in closed loop

-mash on the gas and the ECU is sent into open loop (determined by a number of things primarily TPS and RPM input).

car enters open loop mode, at wide open throttle, your ECU calculates fuel curves based only on MAS and RPM inputs (aiming for an 11:1 air fuel ratio rather than 14.7:1), and then dumps some fuel on top of that to make sure your engine is "safe"?

these fuel curves are selected by the ECU using MAS and RPM inputs, and are taken from a programed table in the ECU. the table was calculated using these values:?

(taken from text)
In order to guarantee that sufficient fuel reached the cylinders, the programmers had to consider fuel pressure, injector flow rate, injector dead time, spark time, spark duration, valve timing and a host of other engine operational parameters, down to such minute as battery voltage. Using these values, they figured out how much fuel could be delivered in a given time, added a hefty safety margin and based their ECU program on that.

as MAS and RPM signals change, the computer constantly matches inputs to the preprogrammed ECU data and changes the amount of fuel delivered during open loop operation accordingly?

this is why when you change anything (such as add larger injectors?) that effects the ECU's values (fuel pressure, injector flow rate, injector dead time, spark time, spark duration, valve timing, ect.) the original program the ECU used to calculate fuel curves is no longer accurate?

 

[steve]

Sounds like your ready to digest the details in the 1G DSM technical manual and learn what Sean glossed over.
You should still be able to download it from http://www.ecanfix.com/~manualcd/index2.htm or just order the Manual CD from www.manualcd.com

Steve