car wont rev past 2500, not maf, no cel

flarrow · 03-17-2010, 10:19 PM

i have a 1990 240sx with a red top swap, i was driving it around fine, then it started acting up on my one day, now it will not rev past 2500 rpm. ive replaced the maf and mafs, checked wiring, checked my ecu for codes, nothing showed up.
So right now im stumped.
any help would be appreciated,
I noticed my cas has a nice crack with a hole in the black plastic.
Could it be my ecu?
How do i test my sensors to see if there working okay?
The car starts and idles fine

240ftw · 03-18-2010, 12:03 AM

my old 240 had a ka in it but i had the EXACT same problem mine was a bad vacuum hose from the valve cover to intake i had a crack in the hose i replaced that and it worked fine. it might be the same thing might not im just saying that was my problem. and i dont think it could be a bad ecu

flarrow · 03-18-2010, 12:57 AM

yeah i was thinkin a vacuum leak or ic piping leak too, ill check that next tomorrow

Thrasher068 · 03-18-2010, 01:36 PM

Read forum come on now what look for my posts and follow them 1 will tell u how to make a leak tester and there is also a pic

flarrow · 03-20-2010, 12:20 PM

well i went out today to start my car, and it wont, switched mafs still nothing, it just cranks, im gonna test to see if i get spark and go from there.

Thrasher068 · 03-20-2010, 05:46 PM

Well Hmm. Check for spark but disconnect all fuel injectors and then pull 1 plug and ground it out see for spark then if u have spark your ignitor and coils good. Then pull fuel rail off see if fuel spraying

flarrow · 03-27-2010, 04:53 PM

i have fuel. replaced my cas cause it was broken. and repalced my ignitor because that was broken too, it barely starts now. idles and like 500 rpm. backfirng and such, tested the spark and it is still very weak, how do i test the coils

Thrasher068 · 03-28-2010, 08:21 AM

When u say u changed your CAS did you realign it correctly? you need to have the #1 piston at TDC, Valve cover off, intake cam mark at 10and another at 12, Crankshaft at 2nd notch from the left on the pully marker line NOT DOT ther should be 5 ( | ->|<- | | | ) That sends the signal to the ECU to spark, Then insert the CAS and you will notice it rotates. There are 2 marks on it 1 linesup before it goes in and then lines up with another after tightin it down, The 2 bolts should be close to center in the slots as possable if done correctly.

If you have backfire then u have a timing issue... so try that... you dont have to fully install the valve cover to test it but you will get oil everywhere if u keave it off formore then 10 sec

flarrow · 03-28-2010, 07:40 PM

I believe i had my timing wrong, i had my crank lined up properly but not my cams. because i dont have the dark links in the chain i went by these marker dots on the gears, but they were wrong, so i lined it up with the little dowel things on the cam shafts and they lined up at 10 and 12 with the crank on the second from the last marker. Hopefully that works

flarrow · 03-28-2010, 08:31 PM

OK got all the timing issues out of the way, but the car still had problems, i believe it is due to the wiring of the ignitor, ive seen a couple of ways of doing it, just gonna try the other way, and see how it goes from there

flarrow · 03-28-2010, 10:45 PM

well i re wired it and it works great!, thanks alot for the help guys