hey guys..i am new to fords. i bought a 90 lx...the motor is a 306 with all forged internals, wildly ported e7 heads, edelbrock intakes, 255 gph pump,70 mm tb, headers, x303 cam, roller rockers. i was told that it had 36lb injectors. the problem is at cruising speeds it has a surge that feels like im riding an actual horse! i was told its because of the 36lb injectors that is was getting too much fuel. at idle it hard to tell with the lopey cam but it sounds like its loading up but when i check the plugs they look great. it does have a stock maf. yesterday i got snnoping around and found the injectors are actually stock 19lb thats why the maf is stock. anyways would the 19lb injectors cause this surge at speeds ? possible fuel starvation causing it? what injectors would you reccomend? i plan on getting a little better head so i want something that will work now and then when i get the heads. it doesnt have an adjustable regulator either which is gonna be an upgrade as well. this is my first ford so im lost at trying to figure it all out...any help will be appreciated....thanks
i dont knnow the mm of the maf..all i know is that its a stock piece , also dont knnow the fuel pressure..it has a stock regulator on it so i imagine its stock fuel pressure
technically if you have the stock MAF and injectors you shouldnt be getting much surging at all even with the stock MAF and injectors , I would probably pull the distributor and check for play in the shaft .....
im going up to 24lb injectors with a matching maf...im told by a local mustang performance shop that with the x303 cam it is common for a surge under 1800 rpms...which is where it surges so i guess its a characteristic of the cam? anyways i am gonna check the distributor also to cover all bases
I used to get surging problems well I still do. but when I was running a MAF sensor if you just turn it little tiny turns it can make a big difference but with that set up i would run 24s at 42lbs at the regulator.
do a vacuum test on it. I eliminated all my leaks and away went all my surges. The biggest culprit was the brake booster, next was fittings and lines.
Kildalls Racing First thing is always check for vacuum leaks. Throw a fuel pressure gauge on it and check the fuel pressure. Check the pump and filter. If you are planning to go to better heads make sure you get new fuel rails and pressure regulator. As far as injectors go 30lbs injectors or 24lbs should be fine. Make sure that if you upgrade don't get cheep junk. 70mm to 80mm throttle body and MAF. You should probably pull the plugs and check to see if they are burning rich or lean (most likely lean).
With a 306 I would look at going to 30# injectors, with my mods i'm hitting about 95% utilization under full load and I have 24#ers. Also, with everything you are doing to the car you should really look at getting it tuned by either yourself or at a dyno from a reputable tuner. This will help with the drivability of the car as it's idle. Then also, you get a tune and then you won't have to worry about getting a fuel pressure regular and you'll know the computer is working off the correct values rather than running from it being tricked. Just my .02, but I know at least 10 fox cars that completely changed after getting it tuned, but they got more horse as well.
I'm having a similar issue - have you got any updates to a solution for your problem?? My car seems to act fine under WOT, the surging and bucking around occurs only under part throttle & cruising. Seems worse when I'm using accessories like headlights, wipers, A/C, etc... anything that draws amps. Anybody got any feeback??
mine does it too, mostly at cruising speed, nothing when on or off throttle. Need to check all vac lines first...of course mine is cammed pretty good and it does come on around 1800 as well
