well, i just joined the FC nation last weekend, but have been there in soul for about 7 years. I picked up a 1989 GXL and now am in process of restoring it to its original condition. Which shouldn't be hard considering the impeccable shape it has been kept in. From the minor body dings, to a solid motor, trans, and a suprising LSD; it's all in more the expected shape. The only problem I'm having is the engine cuts all power or airflow or some other suspect to instant power loss, at 6000 rpm... Now here is the interesting part. If i rev it slowly i can creep up to 8000rpm, but any quick and decisive throttle action from that point on feels like shoving a wad of wet toilet paper straight into my airbox, for lack of better description. Now ive checked somethings out and researched several of the suspects, from my 5th and 6th throttle port actuators to the funny squealing noise my O2 sensor makes when juicing the engine quickly. As far as i can tell, its a number of things. hit me up with an email, or just plain respond to the post with any helpful information. LOOKIN FORWARD TO IT!!

May sound pretty stupid, but make sure the air box isnt actually blocked. If the car sat for any period of time, rodents may have made a home in your airbox.

wait a second. 89 model gxl's didnt come from factory with lsd. i have an 89 gxl... no lsd. O2 sensors dont make a squeiling noise... they cant theres nothing that moves. and to see if your 5th and 6th ports are working right smear some grease on the rod on each one where it goes into the port valve.... drive the car and persistantly keep pushing the rpm's above 5 grand and then chech to see if the grease has smeared... if the grease did smear then they are working, if it didnt then there stuck. but those and your secondary injectors open up at about 3800 to 4000 rpm, so that shouldnt be the problem. my 86 base model has the same problem as yours except mine happens at 4000 rpm due to faulty grounds that i am about to go fix right now...

it might be a fuel filter too

yeah thats what i thought after much deliberation.... but through EXTENSIVE research, the GXL model did not come factory with LSD. And i thought maybe someone had put a Viscous Limited slip into it... i was wrong on both accounts, Although the GXL didnt come stock with lsd, it was a manufactures option. say you wanted to comfort of the GXL model but with the torquey fun rear-end. sure enough i tracked back in my car history and it rolled off the factory with LSD. and the MAF sensory on my model (dont know of others) operates on vaccume,... the less air sucking in holds this spring like mechanism in the center like a plug of sorts... maybe that dead mouse is in there still squealling for his tiny life .......... thanks for the grease test, shoulda thought of something like that https://www.nopistons.com/forums/pub...IR#>/smile.png

How's the exhaust system? Make sure it's not plugged.

just for those of you that are curious and may be having a similar problem.... turns out it is the 5th and 6th auxillary port actuators. Theoretically they pulnge open at 2.5 lbs of pressure, where as mine (after hooking a rigged gauge up and reving the enine) do not even read on the gauge.. maybe a 1/2 lb of pressure being delivered through those damned tined copper lines. in conjunction the valve actuators (have no idea what the are called) operate at a unreasonable 7.75 lbs of pressure. Hooray for old busted ****. thanks for the posts guys.



p.s. exuast in damned new... its a stainless pipe that resonates ohh something beautiful and a shiney cat conv. whoever owned it before me sure got something right

I wouldn't think they would have that dramatic an effect. Shows what I know.