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Project 90 Plymouth Laser RS won't rev past 4,000 rpm while driving.


Probationary Member
Apr 14, 2010
Viroqua, Wisconsin
Well I'm kinda new to this site here but maybe I can actually figure out my problem. I guess I'll start from I first bought the project 1990 Plymouth Laser RS back in the fall of 2006, suppose to have just a bad head on the engine, ok no problem I thought... After buying the car for $600, getting it home with all 4 flat tires (weather checked) & getting the engine head off, I realized it was going 2 be alot more work than just a head swap.:ohdamn: I just decided 2 buy another Plymouth Laser for a parts car to build the good one up.

I had converted the non-turbo engine with high compression pistons 2 run with the stock 14b turbocharger that was originally in the car. :thumb:The build & swap of everything went pretty smoothly. Most of the parts on it are stock, I'm trying 2 get as much power safely out of the stock engine, turbo & drivetrain. Listed below are the currently replaced items...:aha:

-Engine swap.
-Engine conversion. (Non-turbo converted to turbo)
-Pressure plate. (OEM)
-Clutch. (ACT 2600)
-Turbo clip & port. (OEM- 14b)
-Spark plugs. (NGK-gap @ .28)
-Spark plug wires. (7mm)
-Coil pack. (OEM)
-Fuel filter. (OEM)
-Air filter. (OEM)
-Oil filter. (Fram)
-Boost gauge. (Autometer)
-Oil pressure gauge. (Autometer)
-Temperature gauge. (Autometer)
-Voltage gauge. (Autometer)
-Valve cover gasket. (OEM)
-Intake manifold gasket. (OEM)
-Exhaust manifold gasket. (OEM)
-Exhaust manifold. (OEM)
-Custom 2.5" stainless steel dual exhaust.
-2 chrome high flow mufflers. (3.5"+ outlet)
-Crushed 1G-BOV. (OEM)
-MBC. (Manuall boost controller)
-Eliminated throttle body vacuume lines.

That's all I can think of that I have done so far, but onto my problem. In neautral it runs perfect, idles @ 850 rpm with -20 in/vac showing on the aftermarket boost gauge. (Which is normal from what I've researched, correct me if I'm wrong.) Then reving I can either stomp the throttle 5,500 rpm @ about 4 lbs of boost before the rev limiter kicks in or I can carefully get it 2 rev up 7,000 rpms with almost 5 lbs of boost.

That part is fine, it's just when I'm driving in any gear 1-3 I've noticed so far. Starting in 1st I'll let the clutch out, give it gas, starts building boost @ about 2,500 rpm then by 4,000 rpm I have almost 10 lbs of boost but @ 4,000 rpm it sounds like my BOV is activating over & over agian. I can't get any higher rev than 4,000 when driving. So I'll shift into 2nd start giving gas & building boost. Agian @ 4,000 with almost 12 lbs of boost it sounds like my BOV is activating over & over agian. So once agian I'll shift into the next gear 3rd, start giving gas building boost then agian same thing.:banghead::banghead::bandgead:

I have no idea what is goin on now, WTFI've checked over so many things. It seems like my MBC isn't even controlling my boost @ all. Which ever way I turn that knob seems 2 make no difference what so ever. My flapper arm is connected on the dump side & the actuator still works fine connected threw an air compressor. I can feel pressure coming out the stock J-tube on the stock 14b turbo after I rev it up a little bit but it doesn't move the flapper arm very much. I know quite a bit about the DSMs and have never seen this problem before. I'm getting lost on what it could be now. Any information would be greatly appreciated.:pray:
Hopefully I get alot of answers from alot of people & they're all saying the same thing, some easy fix that will take only a few minutes.:D

HELP will be greatly appreciated, Thanks agian-Josh.


Proven Member
Feb 13, 2010
Marysville, Washington
Did you crush the BOV yourself? And why a crushed with stock set up? Maybe in the process of "crushing" it got damaged. Sorry if this didn't help, post was kinda over whelming. But out of it all the crushed BOV seemed to be only noticeable problem item.


Probationary Member
Apr 14, 2010
Viroqua, Wisconsin
Thanks 4 the reply. I've got the "Haynes" Edition of the rebuild book & in there it says that the vacuume needed to open the BOV is like 14-18 lbs of pressure. MY BOV opens & closes fine, its just when Im driving? I did crush it and it did tighten up the spring tension in the stock 1G BOV, which did seem to help the problem a lil bit but still acts like the BOV is activating @ 4,000 rpms? I don't know what to do anymore with this project car???
Thanks agian 4 the help though :) Josh
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