I've posted on crossfire forum everything thats wrong, but I'll try and condense where I am for You guys/girls. Just rebuilt the top end with: chain gears, lifters, springs, waterpump, and comp cams 252ah12 which they claim is for a crossfire. The timing is dead on, it will fire within half a crank. The problem is that the car continues to flood itself to death. I looked for and found every vacuum leak I could find, but it will still flood itself. Right now the only code is 33 MAP out of range, to high. There is plenty of vacuum going to the MAP, and it and the rest of the sensors were fine before I very carefully took the motor apart. Also when it starts to go really rich(eyes watering) there seems to be a misfire? Would this be one or more of the plugs being to wet to fire properly? any ideas, I've already lost a months worth of insurance cuz I can't drive it.

I'm losing my love for this car VERY quickly.
Ash.

 

Check the coolant temperature switch. Also, are both injectors spraying excessive fuel, or just one? Possible leaking or grounded injector. Any wires get pinched in the process? How much fuel pressure do you have? Should be between 9-13 lbs. If it's excessive, the regulator may have failed.

On the crossfire, there will be more than one plug fouled from excessive fuel. If both injectors are pouring fuel in, all 8 may be fouled.

Check those things and tell us what you find and we can go from there.

 

It could be excessive fuel pressure or bad injector(s). But since the ECM indicates MAP voltage problems, it just may be the MAP sensor. Did you clear the codes and check for a recurrence? It may have set on initial fire up, and remained, if not cleared. You say there is plenty of vacuum to the sensor. Have you checked out the MAP output voltage to rule out a bad sensor?

RACE ON!!!

 

Okay guys, just tee'd a vacuum guage between the left TBI where the MAP gets vacuum and the MAP sensor. At a shakey idle I was getting about 7 inches of vacuum and pulling code 33 again. I have 2 MAP sensor that were known to be good, but hey, at this point i almost don't care what a have to do to get it running. Afriend has a spare MAP he uses for testing, I'm gonna borrow it and see what happens. Or do I have a vacuum leak that I can't here or find still? CTS was a new 2 wire that I installed, so I don't think its the problem.

Ash.

 

You need way more then 7 pounds of vacume at idel for the map sensor to work right. Are you conected to maniflod vacume? I am fighting with a map sensor at the moment on my friends TBI system because he only has 14#s. The TBI system is looking for 18 PSI and I suspect the crossfire is the same but mabey CFI will chime in with the crossfire specs. One thing that effected vacume (from 5-15 #s) was timing. Did you set the base timing corectly? Advancing the timing a bit will increases vacume from what I have seen over the last week.


[Modified by FD2BLK, 7:49 PM 6/17/2004]

 

7 inches is way to low. Mine with 1.6 rockers is 15. You still have a leak somewhere. Get out the WD40 and look for more leaks.

 

I believed you when you said you had "plenty of vacuum". Double that would be low. The shaky idle and the high MAP voltage code add up to low vacuum. Is the timing set correctly? The timing chain in phase? Plug wires on the right plugs? That isn't THAT much of a cam. It appears the MAP is reporting the conditions, correctly. Now you need to find and correct the faulty conditions.

RACE ON!!!

 

Sorry felt like good vacuum to my finger!!! I just tried a third MAP and got code 33, so it definately is not the MAP itself. The MAP is hooked up to the same place it always has been, which is the big port on the back of the left TBI, the timing is so good the car(when dried out) will start on half a crank. I am using stock plugs accel coil G.M. performance wires and a hypertech chip. Could the problem be the circuit in the computer that controls the MAP? I have a spare. If I advance or retard the timing from where it is, it not start easy if at all. Well, its 9:50pm now so I guess I'll quit for tonight and let the car 'dry out' over night.

Ash.

 

I have a thought guys. If the manifold pressure is high, than vacuum is low, which will screw up the MAP readings at idle and overfuel the motor correct? If the cam is not in "phase" properly and the valves are closed at the wrong time, will this not cause manifold pressure and low vacuum? I guess what I'm trying to say is, if the valves are not operating at the right time than there is gonna be to much blow(pressure) and not enough suck(vacuum) when the computer thinks there should be, thus screwing everything else up and flooding the motor?

Ash.

 

There is no "circuit in the computer that controls the MAP". The ECM (computer) sends a 5 volt current to the MAP which is altered by the manifold pressure and sent back to the ECM. The ECM factors that reading in sending the proper pulse width to the injectors. The MAP is reporting out of parameter voltages to the ECM, that indicates high manifold pressure (low vacuum). Under low vacuum conditions, the ECM supplies more fuel, because that vacuum is typical of an open throttle. The MAP voltage and the TPS voltage and the rpms don't match, so a code is set. At your measured vacuum readings, the MAP is working correctly and the ECM is properly setting the code. You don't have a sensor or ECM problem... You have a vecuum problem. Correct. I believe I mentioned that possibility is a previous post. I see the light bulb starting to glow.

RACE ON!!!

 

Thanks...................It all started to make sense at 11:30 last night. I'm gonna pull the front of the motor off tonight and get ready to set it up the RIGHT way!! I'll let You know how it works.

Ash.

 

Well I had the front off the motor again and the 'experts' had a look. They say I have done everything right, so the cam, gears, and distributor are properly set? I removed the A/C also, would the fact that the plugs in the harness for the A/C compressor not being plugged in cause some kind of problem? The ECT was in working condition before I pulled the motor apart but........would the massive overheating problem I experienced during the initial running 'cook' the inside of the ECT and caused it to malfuntion?

Ash.

 

A/C wiring will have no effect. ETC??? I still think you have a major malfunction causing low vacuum. Are the valves set properly? I haven't seen compression or leakdown test results. No vacuum leaks?

RACE ON!!!

 

Just posted this on crossfire forum: Its Friday night, just fired(or tried to) the car up after getting it back together again. This time the CTS was unplugged. I watched both injectors and they are fireing MASSIVE bursts of fuel, almost constant down the TBI's!!! The car is drowning in fuel? What should I check for to cause the injectors to dump that much fuel, no codes showed up yet?

Ash.
P.S. I was gonna put a new CTS in, but the old one is frozen into the bloody intake!!

 

try zeroing out the map to about .6.........the cam pressure wave is causing it to over fuel....I had the same problem and this is what corrected it for me....of course I have an accel computer and have that capablity.

 

The injectors are a passive device in the fuel metering picture. The fuel they deliver is a function of fuel pressure and ECM dictated pulse "on time". The pintle in the injector could be blocked open by foreign material or a build up of gunk, but then they would quickly bleed off the fuel pressure and flood the engine when you shut it off. You can try activating the fuel pump with the engine not running as a test for leaking injectors.

With the CTS unplugged, the ECM thinks the engine is ice cold. It will correctly attempt to send the richest mixture to the engine to keep such a cold engine running. Have you tested the CTS? Does it need replacing? After you get the CTS sending proper signals, track down your low vacuum problem.

RACE ON!!!

 

Changed CTS today, still running to rich. Injectors are not leaking, vacuum problem maybe cause by incorrect TB base gasket blocking of completely or partially a needed vacuum port? Gonna hook up a mityvac to the MAP tomorrow and see what happens, will let you guys know.

ASh.

 

There are no vacuum passages between the manifold lid and the TB assemblies. It will be interesting to see the results of the mityvac/MAP test. I suspect a proper signal to the MAP will reduce the excess fueling, drastically. Then, as I said a few times, you'll have to track the cause of the low vacuum. Good luck, and...

RACE ON!!!

 

Heres My reply that I posted at crossfire forum guys.

My reply: Okay, heres the latest. I hooked up a mityvac to the MAP and gave it 15inches(don't be rude!!) the car fired up with NO code 33......or any other code for that matter. BUT its still running pig rich and flooding to death? Either there is still a vacuum leak somewhere I can't find or hear, or the circiut in the ecm that controls flow to the injectors is fried along with it adjusting the timing which could drop the vacuum down and screw up the MAP? Will try the original ECM and stock chip tomroow after I put the TBI's back on. Also noticed that the ICM passages on both TBI's are BLACK, could this be the(or part of) the problem?

Ash.

 

Heres the latest, as of last night(Monday).

The updatepdate: Monday night, installed new TBI base gaskets, ran car........no change. Installed different ECM and stock chip......no change? Could a leak between one or both of the intake to head gaskets and the heads cause this? can't hear any vacuum leaks, but I'm missing 7 inches of vacuum somewhere? Unless the missing 7 inches is because the car can't run smoot enough to create the vacuum I need? Is is my cam choice, I went with what Comp Cams listed on their website. Here are the specs: Camshaft Specification Table
Part Number 12-388-4
Engine 1955-1998 Chevrolet
262ci-400ci
8cyl.
Grind Number CS 252AH-12 (V-8 T.P.I.)
Description

Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.425 0.44
Duration At 0.006 Tappet Lift 252 260

Valve Timing At 0.006
Open Close
Intake 18 54
Exhaust 66 14

These Specs Are For The Cam Installed At 108 Intake CL
Intake Exhaust
Duration At 0.05 206 212
Lobe Lift 0.2835 0.2933
Lobe Separation 112

Recommended Valve Springs 981-16

Chevy 262-400 Computer Controlled 252AH-12 Cam
Code:12-388-4
Price: $163.20
Quantity in Basket: none
HYDRAULIC-For use in throttle body injection, crossfire and TPI 305 and 350 engine.

What do You guys think? I know Your all tired of dealing with this problem, so am I, sorry for the headaches and constant cries for help.

Ash.