Studders when acclerating

[Acid_Burn]

Well My mom has a 1990 Chevy Beretta with the 3.1. This past summer I had to put new injectors into it and she didnt have the money to buy new ones. So what I did was took my old injectors from my 1992 Z34 Lumina 3.4 DHOC. They seam to work fine but when you would be going like 30-50 and want to go faster it would hasitat but then it would acclerat. Now its studding when you stop and try to take off intill like 30MPR or so then its fine. What Im woundering is this due to the injectors or some thing else? If its some thing else what could it be? Oh and would injectors from a 1995 3100 work in the older 1990 3.1? Thanks

[GutlessSupreme]

The ECM isn't tuned for DOHC injectors.. they flow a couple of pounds higher. It's probably running pig rich, stock 3.1s just don't flow quite that much air to combust with It could be a number of things, but I would try getting a set of the right injectors first.

[IsaacHayes]

Yeah those injectors are way too big. And it probably fouled the plugs and now it's running worse because of that. Proper sized injectors and new plugs are in order. Do not get bosch platinums though!! LOL

[powerdoctor]

Oh no...

Now we get to argue about this...lmao

I love bosche plugs.
They are the only plug I can throw 60, 000 volts at with a 500 ohm per foot wire and have survive.

I have burnt/ cracked the inner core to where I can get no continuity between the tip and where the plug wire goes, and still get them to spark.

Now I will say this though...

After market wires ( murrays/ zone ) I have found have an absurd amount of resistance to them.
Couple that with a small voltage coil, and then try to run a bosche plug and you will foul them out everytime.

The bosche plugs have a high resistance compared to normal plugs and that plus the afore meantioned causes fouling, which makes people hate the bosche plugs.

But I put them into Nitrous eqipped vehicles, with turbo's and what not and have found not one problem with them.

I ran a set for 4 months, between 3 different engines and sprayed them and had those puppies so hot I was "dieseling" while idling and had to keep the engine above 3000 rpm so the advance of the ignition would override the dieseling just to get them to cool off and they still worked once they cooled down.

I do agree with the injectors and plugs being your problem though, they are right, change them out.

[jp_grasshopper_007]

are u kidding?

[IsaacHayes]

LOL... bosch platinums wear out so fast. And the GM DIS is not friendly with them the way it fires. Some have bad miss-fires as soon as they install them.

Go for the proper AC delco normal plug or the AC delco platinum or iridium if you want to spend some money. The normal AC delco plugs is all I run and the last set I pulled out were still at the correct gap and they've been in there a while.

[powerdoctor]

I am wondering why it is so hard for a company to make a plug that will live in high horsepower apps and function right in normal cars.

A spark, even an msd spark, should just go across the gap like nothing.

Is it the heat?

The insulator?

I really wonder what is going on here...

Why can't there be an "overall" good plug.


And don't start telling me about " ngk " ... lmao

I have run bosche on many GM D.I.S. systems and have had no problem though ... but I always had race wires on them.

[IsaacHayes]

GM DIS needs platinum on both electrodes. BTW the newer Iridium GM plugs say NGK on them.

[Wiz85]

Know that plugs weren't really the issue here, but it's definitely brought up my interest b/c in my opinion, spark plugs are everything. Because what model of a certain brand of spark plug determines your fuel economy, longevity, performance, etc. So what I have learned is that regardless of what plug I use, I need to find out how to read the model code on the plug.

There's more to it but the heat range should be determined by what kind of application it's used for; boost, cranking compression, chamber cooling, hp numbers? And the resistantance range is determined by how much voltage are you running vs the compression and spark gap, and the therefore predicts you spark plug longevity.

They use AC Delco, NGK as well as Bosch in NASCAR, NHRA, etc, but they spend millions on finding the perfect plug.

[Juglenaut]

Blah blah, get stock replacements in most Daily drivers stocker plugs are good enough, people that put solid core wires on a N/A engine that is under 500hp drives me nuts esspecially if it is a Daily driver that pushes 350hp and expect to hear the radio on AM, oh and probillet ready to run MSD dist. are noisy....

I have used coppers in my Euro since I bought it. I did use iridiums in my 91 gp.

Anyway the fuel flow regulated to allow the proper lbs/hour is regulated using a different fuel regulator, you are now undering flowing by increased regulation, the injectors are at MAP pressures flow charts that would reflect lean in wot, rich in mid-range. The computer may think it is in fuel enrichment for a longer stretch. Suprised it not throwing a code.

[gpse3400]

Those injectors are too big and the spray pattern is all wrong. The walls of the intake ports are most likely soaked. DON'T mix injectors unless you know for sure what they will do.