hey guys a while back i had a question about my car having low boost. to update i ran a straight pipe back to a racing beat cat-back and the problem is solved. it made a huge difference.
so heres my latest problem maybe you guys can help. I have a slight hesitation at 3800 rpms no big deal but then after that at no exact rpms pretty much all over the place over 3800 rpms there is huge hesitation and jerking its not all the time and was there before i did my exhaust but now happens more often. im thinking the secondary fuel injectors but dont really know. any advice would be great
thanks

Dave

 

bump

 

Yeah, probably your secondaries. The open exhaust gives more power by allowing more boost to build. Which in turn makes the secondary injectors pulse width increase to keep the mixture stoich. If they are clogged or just worn out, it will run like **** above 3800.

 

thanks. does anyone have advice for upgrading the fuel system. would it be smart to put in 720s now and how about the fuel pump

 

If it’s only happening above 3800rpm, your secondary injectors will be the first suspects. Unless you plan on replacing them with larger ones now (you will need a fuel controller as well), then get them professionally cleaned. The secondaries only get a small fraction of the total fuel flow over their life so are more prone to clogging.
Also check your ignition leads and spark plugs if they’re not new. I just fixed a terrible hesitation/stumbling problem by buying a NZ$12 generic lead to swap out each lead in turn. The first one I replaced cured the problem completely!

 

any suggestions on where to have my injectors cleaned. I live in PA and though i could let it sit for awhile id rather not. is my only choice pretty much to send them out.

 

I tried a local place in milwaukee that specialized in fuel systems, but they didn't have the pintle caps. I think a lot of folks here would agree, RC Engineering does a pretty good job. I've done two sets through them, absolutely satisfied with the work.

Greg O.

 

any advice on getting the fuel injectors out. im gonna get them off then check em out if they seem clogged ill send them out. also is there anything else i should do while i have everything apart.

 

also did anyone ever hear of having your intake manifold sent out and they run this stuff threw it to make it flow better someone told me about this awhile back.

 

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Are you sure you are not hitting fuel cut?????? That kind of jerk will throw you forward in the seat. How much boost are you showing since doing the pipe thing???

 

it goes all the way up on the stock boost guage now it used to hardly move at all. that would be an easy fix fcd or controller. it is very violent also if i take it up slow i dont notice it that is when no boost

 

oh yeah also first i only took off the main cat then i noticed the hesitation and i was only hitting about half boost on the stock guage. now w/ the precat off also i get full boost

 

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Do you not have a FCD?! I think HAILERS is on to something.

And you used the word "violent"

 

Hey bob13bt where in west virgina do you live? what kind of car you got?

 

no no fcd

 

so do u guys think im hitting fuel cut.

 

I do. Keep it out of boost (or really low boost) and run it over 3800 and see if it hesitates.

 

i noticed that before if i go up slowly it wont hesitate.is it really possible that im getting that much boost w/ these light mods or could something else be wrong causing me to hit fuel cut early?

hks intake
no cats 2.5" all the way to rb cat-back

 

The stock gauge only reads like 6 psi. Around 8.6 is when fuel cut kicks in. It could be spiking that high with your intake and exhaust.

 

so what do u guys think i should do about this

 

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Here's another thing to think about. My 86 N/A was doing a very similar thing, but only after the car had been running for a while. It would run fine when first started, but buck and bog down randomly after a few minutes. Turns out the strainer on my fuel pump was all clogged with rust. When the car would run for a few minutes, rust would get sucked up around the strainer, and the engine wouldn't get enough fuel after the secondaries came on. A new $12 fuel pump strainer fixed my problem completely.

 

where is that located maybe i should replace it just to rule it out and or preventive maint. but say i order a fcd what should i do to prevent boost spike?