schwindty

Hey all, I just installed my 1.7 Roller Rockers as well as I cleaned all my sensors, my EGR Valve, idel controll, and set my TPS to .97V. Everything should be correctly set up other than one of my O2 sensors is busted off. It was dry enough and enough snow melted off my driveway today that I could take some runs down the highway. Just like the last time I was having problems I have nothing off the get go my sister's Hyundia does WAY better than my mustang from 0-50 km/h then when I hit around 3 thousand RPM it just takes off usually the tires break loose at 3000 RPM when the power hits. I am lost at what this could be from everything is in working order. The only thing that it could be is my computer system due to the fact that it is a Speed D and I dont have a chip burned yet. Could someone help me out in any way or advice would be appreciated

schwindty

Anyone had this one yet> I have searched the engine with no luck, someone must have some feed back

92BOOSTED

Your speed density must be going thru some shock with what you've got, it doesnt know what to do.
Have you checked your timing yet?
Also you need to get the O-2 sensors replaced. Try that, but i know you need that chip or you need to convert to mass air.


Rye

Quik

problem is going ot be the SD. you got to many things SD doesnt like. one being 24lb injectors other is heads. your going to have issues for some time to you get rid of it or get a proper tune

86HOGT

Yeah what were you thinking!? J/P...but before I'm doing anything internally engine wise, I'm converting to mass air flow, you should do the same as it's getting past due...

IownaMustangNow

newbi question but what exactly is speed density?

roundman

speed density is the fuel injection control system used up until '89 in all cars except those sold in CA which quit using speed density systems in '88. in the speed density system, the air flow into the engine is not actually measured by a mass air flow meter like it is in the MAF system which replaced speed density. the ECU is programmed to "imply" what the air flow is by using the TPS and MAP sensors to estimate the air flow and then add the fuel needed for proper operation. the only way it can do this correctly is if the stock cam and heads, etc. are used as this algorithmn in the ECU is complicated and any change away from the stock parts throws it off and it can compensate well for the changes. in the newer MAF systems, the air flow into the engine is actually measured and the computer can respond much better to parts changes and still control the air/fuel ratio properly. the only real drawback to MAF is the flow restriction posed by the meter in the inlet air pipe but this is easily overcome by changing to larger MAF meters.

schwindty

As for my o2 sensors they only effect drivability in cold temperatires once the engine is a WOT it goes into closed loop so that cant be my problem as when I took my car out I was at WOT. I know I have to get a chip burned and one is one the way should be here within a few weeks but I really dont think that it would make that much of a difference and if it does I will be a happy man. Yeah timing is set at 15 degrees with the spout connector out running 104 octane. As for switching to MAF I have considered it but when the engine is at higher RPM's MAF has a tendensy to run the engine lean, and due to the fact that my duration on my cam is below 50 Speed density would not be a problem at all other than my 24lb in which my Chip will accomadate for. Soo i guess I am still where I started I just need to try out that new chip. Unless anyone else can shed some light on my situation.

Thanks

white93 GT

you know i have kinda the same problem....once i hit around 3 grand my car kicks hard and pulls....but its not that bad up to 3 grand its just a very obvious power gain one it reaches around there

schwindty

Yeah my car when I hop on the gas feels like it wieghs about 12,000 pounds. Its terrible and I just can't figure it out because it should be able to shred the tires. Once I hit about 2800 RPM the tires break loose a little and it takes off and its really pissin me off.