runs rich or bad/ tuning problems

ndiiorio

Registered User
just finished putting everything back together after a year. started it up and runs fine but it is definately running rich. after i plug in eec tuner, car barely runs and then is fine and is bad again. i thought it was the chip so i took i to a shop to have them make one. after installing their chip it does the same. am i missing something here? finally i do have a check engine light and it is referencing low voltage at the maf. i tried a different maf sensor and i get the same thing. i need some help... thanks
 
Aloha


I was told that when the head gaskets go you need to change the O2 sensors...........I still havent got mine together but noticed in your old post that you had replaced your head gaskets recently......

Dang I wish I was in Hawaii today


F1
 
make sure the contacts are clean. They have a wax coating on them. Mine did the same thing. Get some 200 grit sand paper and sand the wax off, then use some alchol to clean the copper.
 
i have all new sensors, except for the maf sensor which is used. the eec board i have was used, so it was ready to go. the sct chip from the shop i didnt actualy install, they did. so both of us had the same problems. the shop is pretty reputable for mustangs and im pretty sure he knew what he was doing. i will try cleaning the eec tuner again and see what happpens. i was just wondering if i was missing step going into the install or there was something special i have to do. i still have no idea why im gettinga low voltage on the maf.

yeah the weather is great, but i have seen better days...
 
i will give it a shot later today to see if it makes a difference. it would seem that if it where the contacts on the computer portion that it wouldnt work with anything though, even if i didnt have a chip. and it runs good without any chip attatched, but this definately needs a tune.
 
When i got my tuner, i had the same issue and same codes. I cleaned the terminals off, but not good enough. I really had to get in there and scrape off the wax coating on the stock board before the tuner would work properly
 
A 1990 does not have a wax coating (actually it's silicone on the 91+ years). instead the 1990 has a grease coating that needs to be wiped off with electrical contact cleaner or brake clean and then only a light sanding of the contacts to make them "bright", no more. The EEC tuner has connectivity issues but an SCT chip will not. Do not sand any more off the contacts or you may risk a loose connection. The chip should be very snug. Also make sure that the chip does not contact the EEC case. You need to trim the case slightly to ensure that the contact strip does not accidentally hit the case.

Then some info about the car will help us answer questions. You have been too vague at this point for me to help beyond that. You will also get more help if you post tuning questions in the tuning forum. ;)
 
thanks, i havent done anything yet so i wil just take it back to the shop and see if they can figure something out, im at the point where i know nough to really make it worse.
 
ok as far as mods... 255lph fuel pump, new fuel filter, adjustable fuel pressure regulator (not sure on the pressure at the rail), new maf sensor, 76mm maf with sampling tube for 38# injectors and 38# injectors, 85mm throttle body w/ new tps sensor, s port on super charger, with 5%od pulley, 5% jackshaft pulley, new crank and cam sensor, new balancer, underdrive crank pulley, ported and polished heads, new rods, beehive springs, scorpion roller rockers from scp, new spark plugs and wires, new screaming demon coil pack, new motorcraft dis module with the heat sink compound, new kooks long tube headers w/ new O2 sensors, no cats 3" out to (1) 3" to dual 2.5" to flowmaster 40"'s, new water pump, griffin radiator, new 180 deg. t-stat, new hoses, new gator back belts, new belt tensioners, no vac. leaks, ive been maxing out around 13psi according to the stock boost gauge, new battery, new alternator, and cel reading low voltage to the maf.... i think i got everything there.
 
What sample tube is it? Check the color on the end of the tube. Also check the EEC for adequate clearance around the chip. Let us know what you find out. Are there any other codes? Is the MAF code a constant code or a memory code?
 
alright... sorry it took so long between the time change and my work schedule nothing ever gets done fast around here...

i have an orange sampling tube and the code is in continuous memory... i get code 66. i erased all codes and reset the computer. i let the car idle for about five minutes. the cel light came on and agin i get the 66. i should probably say that before i did any mods i was getting either code 66 or code 65, but at that time i was having other problems as well. i have changed the maf sensor itself and the code remains... is there a computer issue? maybe possibly a ground issue?
 
Possible ground issue. Check the O2 sensor ground on the back side of the driver's cylinder head. It is often missed or even broken and ripped out of the harness during headgasket or engine replacement. It is a single orange wire with a ground loop on the end which comes out of the wire harness at the back of the motor and bolts to the back of the cylinder head. Code 65 points in that direction.

The code 66 is normally caused by an incorrect AFR at idle but normally it would be lean. How do you know it is rich?
 
well im guessin its rich from the smell, and my gas gauge going down significantly... i will try to check that wire today. i know exactly which one you are talking about. i know i grounded it i will have to se if itcame loose int he harness.
 
Possible ground issue. Check the O2 sensor ground on the back side of the driver's cylinder head. It is often missed or even broken and ripped out of the harness during headgasket

Nice one....If I didnt read this today chances are I would have missed it too....


Thanks

F1
 
well im guessin its rich from the smell, and my gas gauge going down significantly... i will try to check that wire today. i know exactly which one you are talking about. i know i grounded it i will have to se if itcame loose int he harness.

A car that is lean will stink also. Rich burns the eyes, lean doesn't. A low MAF signal would result in a lean condition. However, if the MAF signal is not there at all then the EEC will default to an OE assigned fuel table which will mean the car will go very rich due to the bigger injectors. If the ground is there then it may be that you have an open circuit in the MAF wiring. You'll need to check the MAF signal at the EEC to verify that it matches the value seen at the sensor (which should be around .7v at idle and increase with rpm/load).
 
check the O2 wire on the back of the head and its good. i havent got that code since i put everything back together, i was getting it (65) and code 66before i blew my headgaskets. the only code i have now is 66. i was just wondering if it would be something with the computer ground or voltage (harness) since both chips act the same way when installed, and i thought there may be some stepped that i missed before installing them. i did the eec tuner, the shop did the sct chip (i did not buy the chip so i dont have it). i dont know where to go from here in order to get a tune. could it be a computer problem? i have no problem buying the chip or geting from one from you dave but since i already have the eec tuner, i figured i would use it. but it seems as there is an underlying issue i need to take care of before i put anything in there.
 
which wire is in the eec for the maf, and what voltage should be at the maf? how muchof a tolerance is acceptable for the .7v i mean if it is reading low than is .5v to low or would it have to be almost nothing? could this also be the problem iwth adding the chips? if there is no voltage are the chips trying to react with that as well?
 
which wire is in the eec for the maf, and what voltage should be at the maf? how muchof a tolerance is acceptable for the .7v i mean if it is reading low than is .5v to low or would it have to be almost nothing? could this also be the problem iwth adding the chips? if there is no voltage are the chips trying to react with that as well?

At your MAF sensor the wire will be blue with orange or blue with red stripe. Test the wire there with the engine running and rev the engine. Observe the readings. Verify that voltage does fluctuate with throttle and record the idle value.

Go to the EEC and check the same wire and verify both idle voltage and that it varies with throttle the same as the MAF wire did.

The chip doesn't react with anything, it a static device that merely replaces memory values with new ones. If the EEC's routine is screwed up due to a bad sensor then the chip will always be screwed up in the same way.
 
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