chevyguy1969

iTrader: (7)

Hey Guys,

Well I have been chasing a demon that I can not get out of my car. Here is what happened. About a month ago I blew the internal seals of my fuel injectors because I had my fuel press at 50psi. Of course it ran like total crap because it running way rich. I still had my old stock 22lb L98 injectors so I sent them off to Rich at Cruzin Performance and had them cleaned and flow tested. I installed them and set the fuel press to 40psi. The car still ran rich so I installed some new spark plugs this morning because I figured the ones I had where fuel fouled. I also installed a new set of plug wires (8mm Taylor Spiro-Pro). I have a fairly new cap and rotor and my fuel system is in good condition. 2 weeks ago I gutted my cat and got some throttle response back but it is still loading up and running rich. The car is driving very sluggish and hesitates at low RPM and going from a dead stop. I am not getting any SES light and it is not throwing any codes. Are there any sensors that might be damaged from it running rich and so bad after my injectors when out? Do I need to get a new high flow cat and have it put on? I have been driving the car so it is driveable but it has no performance what so ever. Can anyone give me any more ideas?

chevyguy1969

iTrader: (7)

Also, I reset my base timing to 10 degrees advanced if that helps.

DannyT

Are you disconnecting and plugging the vacuum line from the AFPR while setting the fuel pressure?

When was the last time you replaced your O2 sensor?

How are determining that you are running rich? Exhaust? Scan tool readings?

xanax

your injectors are probably beyond repair. i got some "serviced" due to a bad hot start problem. got the "serviced" injectors back and same thing. got some new accels the next week, problem solved since last august.

chevyguy1969

iTrader: (7)

I have never changed my O2 sensor. Could it still be bad even though I am not getting a SES light? The injectors I have now are my old 22lb injectors. I had taken them out because they where leaking and put in some LT1 injectors and those are the injectors I blew the seals out on. I had Cruzin Performance do the work on my 22lb injectors and once they where cleaned and tested they worked and flowed correctly, all within 3% of each other. Yes, I am unplugging the vacuum line from the AFPR. I have tried turning it down to 38psi but then it seems like the car runs even worse so I have left it at 40psi.

chevyguy1969

iTrader: (7)

I have talked with several sources about my O2 sensor and they have said that if it was bad it would be throwing my SES light. Does anyone else have any other ideas? Should I think about getting a new catylitic convertor put on? Any other sensors I should try testing or adjusting? Could my TPS have anything to do with this? Any suggestions or idea will be greatly appreciated.

Jim85IROC

iTrader: (2)

Find better sources. My Jimmy ran so pig rich that I dropped from 20mpg to 13mpg and never threw a code. My IROC ran so rich (from other problems) that black sh*t dripped out my tail pipes, but that still didn't throw the oxygen sensor out of whack far enough to set a code.

The oxygen sensor needs to get pretty bad before it'll throw a code. A new sensor is cheap and they're easy to change, and since they are considered a 30k mile replacement part, you're WAY overdue.

Cruzin Performance has a fantastic reputation and I seriously doubt he'd send junk injectors back to you.

chevyguy1969

iTrader: (7)

The O2 sensor sounds like a good try. My car has over 160K miles on it. The car does run better since I put in the injectors from CP and the new plugs have helped. I will try putting in an O2 sensor this weekend and see what happens. I know CP does great work because so far this is the best the car has run ever since I blew out my LT1 injectors. I will give an update on saturday or sunday.

Beefy89

Are you running a cooler thermostat?I'm running a 160* thermostat and my car runs rich most of the time...Unless I'm sitting still my car doesn't run hotter than 160*..
Just a thought..

chevyguy1969

iTrader: (7)

Yeah, I am running a 180 degree thermostat but I have never had it giving me any trouble. I put in the new O2 sensor this weekend but I can not tell you if it fixed it or not since my starter went out!!!! It has been dragging for the last week so it didnt really surprise me. Unfortunatly I am having to have it towed to my friend's shop today since he has air tools to drop the Y-pipe to get the start out. Once I get it back tommorow I will give an updated report.

laurie

Had the running rich problem recently. Car is a 305 tpi engined Z28. On the front of the block underneath the MAF there is two sensors. The one on the right is the manifold air temp sensor, check it with an Ohmmeter if it is open circuit its Kaput and the engine thinks its -40 degrees. Quick fix is a 200Ohm resistor taped to the plug in circuit and the motor now thinks its 160degrees no more rich running. Long term fix new sensor. I paid £15 inthe U.K. for mine------- sorted.

Laurie

chevyguy1969

iTrader: (7)

Here is an update. I got a new starter in my car and man what a difference, it starts right up! Well its still running rich and kinda running crappy. I will check out the manifold air temp sensor this weekend with my Ohm meter but do I need to check it with the engine warm or cold or does it matter? When I pulled out my plugs 2 weeks ago I noticed that the #6 plug looked like it had black dust all over it, the others looked normal so I think I might have a problem with that cylinder. So far the car is running good enough to drive but its not running right. If I drive in 3rd gear at 60mph, I can definitly feel a consistant little "pit" in the RPMs. I think it is that #6 cylinder giving me a dead miss. I am going to check the sensor this weekend and test my cap and plug wire. I have been wanting to upgrade my ignition to MSD or the Crane Fireball iginition. I will post my results this weekend from what I find.

90Formula-X-F

The O2 sensor with that many miles on it is probley lazy at best. It couold be your problem but doubtful. Look for the problem to be where this all started. The injectors.....

chevyguy1969

iTrader: (7)

I replaced the O2 sensor on saturday, I just was not able to start the car after I put it in since the starter went out. If the problem is the injectors, how do I lean them out?

Dyno Don

iTrader: (7)

Go here:https://www.thirdgen.org/techbb2/sho...hreadid=171848

chevyguy1969

iTrader: (7)

Thank you for the link Don but I had already checked it out. I know my injectors are good bcause they where flow tested and leak tested at Cruzine Performance. Rich sent me the print out of the results with the injectors. I want to test the MATS this weekend and see what it happens. Who knows... when I un-plugged it I might have damaged it when I was changing out my injectors. At this point and over 130K miles anything is possible. Once I know more I will post it.

chevyguy1969

iTrader: (7)

On the manifold air temp sensor, are you sure its located on the front of the block? I know there are 2 sensors there, one is the coolant sensor. I know there is a sensor on the bottom of my plenum towards the back, is this the sensor by chance? When I called my friend at the auto parts store they do not show this sensor or the position its in. They think I am talking about the coolant sensor and I am not. I know one of the sensors is a 2 wire and teh other is a 3 wire or 3 prong I think. Can someone verify this for me?

Jim85IROC

iTrader: (2)

If only one of your plugs was black and the others were ok, it sounds like you may have an injector that's leaking, or stuck open.

BTS88IROC

Your MAT sensor should be in the back of the plenum underneath it. You will have a couple of sensors in the front of the intake, one I think is the coolant temp sensor and the other is probably the cold start switch since you have an 88. I think there might be one more. Some correct me if I'm wrong.

Also the mat sensor is a 2 wire connector.

chevyguy1969

iTrader: (7)

Thats what I thought about the MAT. If its a "manifold" air temp sensor, it would only make sense its located in the manifold/intake. I will perform a leak down test this afternoon when I get home and report my results. This should open or eliminate the possibilty of a leaking injector.

chevyguy1969

iTrader: (7)

I preformed a leak down test. The guage pegged at 39psi since I have my fuel press turned down. After about 5 minutes it had only dropped like 2psi and I was doing some other stuff. After about 15mins it had droppped to 29psi and never dropped any lower. I still need to test the MAT sensor which I will try to do saturday or sunday.

Dyno Don

iTrader: (7)

I had another one today, it turned out to be a bad EGR solenoid.
Disconnected the vacuum line to the EGR and it got better then I checked for fouled plugs and found a couple, I changed them and everything came back to normal 128-130 INT 130-132 BLM. This was on a '91 Formula 350 TPI.

Ant87IROC

Hey, I think I have a bad 02 sensor... put it on the scanner and its saying it needs to lean out, so its running very rich, you can smell the gas. What size wrench is used to remove the 02? I've tried everything, nothing seems to fit. Is it metric?

chevyguy1969

iTrader: (7)

Hey Ant, you will need to go to a auto parts store and buy a O2 sensor socket. Its really deep and it has a slot in it for the wire to go through. Just ask for one, they are like $5.
I did not have a chance to do anything to my car today but I will try the sensor testing tomorrow and see what I find out. What do yall think of the pressure of my injectors?

chevyguy1969

iTrader: (7)

Its 9:35am here in Austin TX. I went out and tested the right hand front sensor on the block and I stand corrected, it is actually screwed into the very bottom of the manifold. I checked it for continuity (complete circuit) and it gave nothing. I also check the sensor under the plenum and it gave nothing. I do not know if this is correct for the plenum sensor but as mentioned below, it sounds like the sensor on the front of the engine is bad. I am running to the parts store around lunch time and I am going to get both sensors if they have them and put them on. It looks like it might rain today so it may be tomorrow or the next day till I can get to them. I will post more as soon as I have it. Thank you for everyone's help so far, I really appreciate it.

chevyguy1969

iTrader: (7)

Update: it turns out the coolant temp sensor in the front of the block and the manifold air temp sensor on the bottom of the plenum are the same part and #. Borg Warner # WT3000 $17.69 each. Both are now replaced and it seems like it fixed the problem of it running rich because i dont smell gas like I used to and I seem to have more throttle response and it starts even quicker, like less than 2 turns of the motor. I still have a miss some where but I will work on that through out the week. I will pop off my cap and rotor and inspect them and check my wires. If anyone has any more comments or suggestions I will keep checking the thread daily. Thank you for everyone's help in figuring this out.

chevyguy1969

iTrader: (7)

*DONE!!!! I am sorry it has taken me so long to post an update but I got it figured out. I popped off my cap last weekend and inspected the brass contacts. They where literally covered in this white acidic foam that had almost eaten them away. It turns out, back when I put it on about 6 months ago it was squealing after the first day of driving it so I put a dab of dielectric grease on the terminals. Drove it, it drove fine and I never thought twice about it. I talked to my friend Travis about it and it turns out you ARE NEVER EVER supposed to put dielectric grease on contacts that are under an "arch" situation. It is ONLY for connections that are constant like spark plug boot connections etc. So I put a new cap and rotor on, it fired right up and not only runs like a tiger but purrs like one at idle and cruising! Plus, I have even more throttly response and combined with the hollowed out cat the car has a really good sound to it. I drove it from Austin to Dallas this weekend and used just a little more than a half a tank so I know my mileage has improved. This is truly a great day for me since my car has not run right for the 2 months. With the help of all of you and my friends around here my car is back up to speed. Now I am curious what kind of time I will run since I have had the injectors all cleaned and flow matched and the cat is hollowed out! Thank you again for everyone who helped out and posted info and suggestions for me.

dboersma69

Did the problem ever return? I have the same problem with my 87 iroc l98. it's only got 20k miles on it, so replacing 20 year old sensors are probably a good idea. I've replaced everything else! The dealer replaced the ECU because they said it thought the engine was always at 240 degrees - made sense, but the problem returned after only a week. Makes sense the sensors are bad..... where exactly are the temp sensors and does the upper plenum have to be remove to get to them?

thank you,
Dave