3500rpm secondary injector cutoff
 

I have a problem. I have an 87 turboII and it'll be driving fine i can have the gas pedal to the floor and the car will pickup perfectly i can here the turbo and everything until it gets to 3500 rpm's it will be like if the car isnt getting any gas at all. I took it to a mechanic and they said it was something with the secondary injectors. What could be wrong?

so it wont rev past 3500??? or does it hit a brick wall, then keep accelerating?? mine hits a brick wall @ 3500 then keeps going! its wierd, mine doesnt do it all the time, just most of the time! it wont boost past 8 lbs. , then when it goes away for a few minutes, it boosts to like 10-12 lbs..... really wierd

look up 3800rpm hesitation because thats when the secondary injectors kick on at. Also there are a lot of differant reasons why this happens but what most people find is that all your grounds under the hood need GOOD cleaning. This is just one example just do a search to find many more reasons and solutions or you may just find more questions :)

check injector connections, check wiring, check resistors by pass front end of bay.

You need to be a bit clearer on the problem. Is it hesitating briefly, or will it just not rev any higher no matter what? If it's just hesitating then this is a common problem. Search for "3800rpm hesitation" and you'll find all the info you need. If you can't exceed 3800rpm at all (that's when the secondary injectors come on), then you probably have a loose injector clip or two.

It just stops getting any gas at all, but ill check those threads now

So would me just un plugging the boost sensor and plugging up the vaccum line work as said in another post?

no. if theres a loose clip on one injector, it shuts both of them down. if you find some way to bypass this (odds are i dont think you can) you could blow your motor up pretty much. you need a multimeter.. or... at least get down there and wiggle the connectors, may be corroded contacts.

Not quite right. When the secondaries are brought on line, all four injectors fire at half the pulsewidth the primaries were firing at immediately beforehand. This means if the secondaries fail to fire, only half the required amount of fuel will be injected and the engine won't produce enough power to allow any more acceleration. The engine will feel like it's hit a limiter.

could i eliminate the secondaries by adding 50% fuel to the primaries?

No. Hell no...

its like if the gas gets cutt off i guess you can say it's a wall, but would it just be a loose clip or would it be the grounding like in the 3800 rpm cutoff? if so what is it that needs to be grounded

sounds like a bad injector resistor pack, assuming that all wiring is good and the injectors all plugged up, and the injectors are good. they'll cause the secondary injectors to not come on at all and you can't get it to go over 3600-3700 rpm while under load. i had an 87 t2 that did the same thing and i replaced it and voila...fixed the problem. if your car was made before 6/87 it has one and after that they didn't use them on the car anymore. it's located under the airbox on the passneger fender well. it's a little silver box with one connector.

not to hijack this thread but i have noticed the 3800 RPM hesitation was WAY more pronounced after i built my engine, i'm wondering if porting is pronouncing this problem and leading people to think it is something else, anyone else concur with this theory? :)

The 3800rpm hesitation is purely an electrical problem, in your case probably caused by not reconnecting a ground wire properly (or something similar) when reinstalling the engine. It'll have nothing to do with the rebuilding or porting.

it is always possible that you have a bad connection from moisture causing corrosion. that happened to my tps, apparently i spilled coolant on it, and it rusted so i had to clean the connector.

i'm actually fairly clean but i will double check my grounds to be sure.