New to DSM's

[KevD]

Hey guys, I'm new here and new to DSM's in general! I have had my Laser just over 2 months and believe it or not it is the very first DSM I have ever owned. It was not taken care of mechanically and I'm sure it can be resurrected to its former glory with time and patience which is why I come here After reading over the site looking for a solution to a specific problem, I have concluded that this MAY be a possible venture.

On to the issue at hand. As I couldn't find the solution, I figured I'd ask. The car runs perfect(considering) MOST of the time. What puzzles me is what happens when I try to "play".

I can drive with moderate acceleration without issue as long as I keep my shifts to around 3500...any higher with hard acceleration and I run into what seems akin to a "fuel cut" or "limp mode" type of thing that I have read here more times than I can count!

I can make this happen any time I want by launching hard through 1st and 2nd with high 4K shifts but once part way through 3rd it just cuts out...never stalls or dies...just cuts out....

At this point, my only viable throttle range is between roughly 1400 and 1900...and if I leave my foot on the throttle will cut at 1900ish and "bog" till 1400ish then kick back in till 1900ish and start the cycle all over again.

NOW, oddly, I can more often than not get it to snap out of its funk by engaging the clutch(while driving) and revving the crap out of it....

I sorta suspect either a TPS or the ECM as the fault but wanted to pose the question to the masses for a little reassurance...

Thanks for any and all assistance that anyone can provide

 

[Josh2g]

It is very unlikely you have fuel cut on a non turbo car, along with what you already suggested try changing the MAF out.

 

[dsm03]

check your IAC

 

[KevD]

It is very unlikely you have fuel cut on a non turbo car, along with what you already suggested try changing the MAF out.

totally granted there!!......thats why I described it to be very similar as thats what its like when driving and it suddenly "hits a wall" like what is described by others who do experience the fuel cut issue.

 

[KevD]

check your IAC

Can you explain the relation there? I'm not questioning your response, just want to clarify how the IAC has an effect on an open throttle situation is all.

Forgive me if that sounds rude, it is not my intention.




Tapatalk for BB!!

 

[fretmelter]

Hey I'm new to DSM's too and ill be getting one this week. And strangely it has a very similar issue. Hope you get it figured out, and maybe it will help me figure out my issue.

 

[KevD]

Hey I'm new to DSM's too and ill be getting one this week. And strangely it has a very similar issue. Hope you get it figured out, and maybe it will help me figure out my issue.

Glad to know Im not the only one. Any and all info that I discover will most definitely be shared here.

 

[kmetiuk]

I question the IAC thing too since you can disconnect it entirely and the only effect it has is that it will idle at a different RPM.

I'm guessing no engine codes either, so I would guess that you have a sensor that is going bad or that you have a short in a wire somewhere. Probably not a bad short, but something maybe grounding out?

I had a short in my main harness about a month ago, it would kill the motor under hard acceleration in reverse immediatly and very now and then kill it while driving normally straight down the road. The short itself was not a cut or nick or anything like that, just looked like a rock or something had gotten in the middle of the harness and eventually rubbed a hole in 2 wires.

 

[KevD]

I'm guessing no engine codes either, so I would guess that you have a sensor that is going bad or that you have a short in a wire somewhere. Probably not a bad short, but something maybe grounding out?



I had a short in my main harness about a month ago, it would kill the motor under hard acceleration in reverse immediatly and very now and then kill it while driving normally straight down the road. The short itself was not a cut or nick or anything like that, just looked like a rock or something had gotten in the middle of the harness and eventually rubbed a hole in 2 wires.

That is correct...not a code to be seen!!! And wiring harness issues I know all too well about being in the field I'm in and working on the highway trucks.


I've got an ecm coming for it and am still tracking down the other parts. Haven't had a chance to check the tps yet either.



Tapatalk for BB!!

 

[kmetiuk]

Weird tho that no codes are being thrown.

 

[mnim15]

Check your base timing.

 

[kmetiuk]

Check your base timing.

^^^^ Agreed.

 

[KevD]

Not all that weird if there really is an ecm issue. Ill get those tests dealt with tomorrow at work (shhhh don't tell the boss) so hopefully ill be able to determine a fault. I've also contacted the old owner and it appears he has a "parts" car in an out-of-town location!! I've asked him to have the ecm, tps, and maf sent in to me to test. Will see how THAT works out...

Tapatalk for BB!!

 

[DSM1G90]

1.8L, or a 2.0L you got there being an NT? Fuel filter changed recently? Sound like you got fuel issues, and/or timing issues..

And plugs gapped at .044 using BPR6ES-11's for both motors..

-DSM

 

[KevD]

Sorry...1.8...thought I addressed that already but I guess not.......my bad...

Less than 500km on new fuel filter and haven't pulled plugs yet...

Like I said...haven't had time for major tests but today some of those are getting done...


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OK...i pulled the MAF sensor and wanted to know what THIS is...

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its inline downstream from the MAF.... does it serve a purpose????

checked the plugs....looked good and are of the correct type but were gapped at .040 so I cleaned them and regapped them at .044....plug wires leave something to be desired so i may just do a plug and wire change along with cap and rotor....general mainenance stuff....

 

[KevD]

Lol....awesome....we have a mystery part!!!....

Tapatalk for BB!!

 

[DSM1G90]

(I bet you have some nice "christmas tree" lights down by the spark plugs if the wires are bad - sparking direct to ground..and why of your 'cutouts' )

Not downstream, but upstream - It's mounted at the top of the MAF. Some users take that thing out, but with a 1.8, leave it in.

it just helps to get the airstream in a straight line before it hits the sensors in the MAF-being a Karman Vortex type of MAF sensor which needs a straight stream of air to be sensed..

 

[KevD]

If its to be upstream....then it was clearly in the wrong spot as it was in the horn on the BACKSIDE of the MAF.....which is why I specified it was downstream....not sure there is anywhere else TO put it...my entire MAF unit is inside the air filter and then that thingy after it...

No light shows to speak of....yet....but then I'm not looking at it when I'm bookin down the highway either...

Tapatalk for BB!!

 

[DSM1G90]

....the MAF from my 1991, 1.8L ... to show as reference (not to cause hard feelings, of course, and you're right - downstream.. sorry on this ... my bad as well -working too much on little sleep) ..

The Honeycomb is what straightens out the airflow to the sensors and this thing returns the airflow back to straight after being disturbed from passing by the Harman Vortex unit. But, some users take this thing out to claim better airflow.

..My apologies - DSM

 

[mnim15]

Do you have any noticable exhaust leaks before the factory O2 sensor? Not sure how OBD1 cars handle it, but my 2G did not like that.

 

[KevD]

....the MAF from my 1991, 1.8L ... to show as reference (not to cause hard feelings, of course, and you're right - downstream.. sorry on this ... my bad as well -working too much on little sleep) ..

The Honeycomb is what straightens out the airflow to the sensors and this thing returns the airflow back to straight after being disturbed from passing by the Harman Vortex unit. But, some users take this thing out to claim better airflow.

..My apologies - DSM

Bu no means are apologies required!!........I just wanted to make sure we were on the same page. And yes, I too have removed this thingy. Oddly, it does SEEM to have improved upper RPM response....but that may just be in my head ...i can shift at 4K now without it acting up...

I came to a realization on how to better describe what its doing....

While driving, hold a higher rpm (3500 or higher) then suddenly let off the throttle... if you sit in this decel state for long enough you will notice two different stages of decel which I thought was weird...its that 2nd state that I want you to pay attention to as thats exactly what it feels like its doing even though I still have my foot on the throttle....

dunno if that helps at all.....

and no....i dont have any exhaust leaks before or after the O2....

talked with the previous owners father-in-law about all that was done to it(he is my service manager)... he tells me that he himself did the following:

- new head gasket - although it needs another as its leaking oil externally
- new timing and balance shaft belts
- new downpipe with flex
- cat delete

all this was done within the last 2 years and car has seen very limited kms since and had been sitting almost a year before I got it...

 

[DSM1G90]

..course, when the throttle plate gets closed, the injectors shut down as well..

Have you checked the play in the "t-cable"? Their should be enough play in the cable where their should be 3mm of play before the throttle plate opens. What sounds like the cable isn't allowing the plate to close completely when you let off the pedal - maybe why you have these "stages" of decel...

How you adjust the cable is loosen the two 10mm bolts that holds down the cable mount on the INT manifold. and move the mount toward the throttle plate where the cable has about 3mm of slack, or 8mm of vertical slop.

This will allow the needed play to ensure that the throttle plate will completely close.

Try that, or see how what your setup looks like ... Good luck .. and THX! - DSM.

 

[KevD]

Ok....that makes sense. I will check on that adjustment along with the other tests I've yet to do..

Soooooo.....given that info....it would seem that to me that the injectors are intermittantly shutting down under a sustained WOT situation.....but WHY is still yet to be determined...

Getting closer I'd say......

Tapatalk for BB!!

 

[DSM1G90]

maybe you're getting what's called "fuel cut" - do a search on this one.

It's designed to prevent the motor from self destructing under extreme conditions. Little 1.8's (1755cc motors) aren't designed for WOT conditions, but just for fuel economy and DD driving - why they built the 2.0 which is a lot more durable and powerful for this area ..

-DSM

 

[KevD]

maybe you're getting what's called "fuel cut" - do a search on this one.

It's designed to prevent the motor from self destructing under extreme conditions. Little 1.8's (1755cc motors) aren't designed for WOT conditions, but just for fuel economy and DD driving - why they built the 2.0 which is a lot more durable and powerful for this area ..

-DSM

hmmm...I was under the initial impression that fuel cut was an unlikely possibility in a N/T car....

if this IS caused by fuel cut....then that just plain sucks ass!!

There has GOT to be a way around it with this motor...... even though its not for it, it would still be nice to have some fun with it....until i can get my hands on a tsi