Jeffrey Fontaine

I'm trying to solve this on my own. Here's what was replaced 2 yrs ago, and we've only driven 8,000 miles since then.

TPI 305/auto, 138k - only mods are K&N's and an Edelbrock cat-back
Plugs, wires, cap, rotor
O2 sensor
Cat converter

Since some point last year, the SES light comes on for insufficient EGR flow, but its never affected the car's driving. In the last couple months, sporadically, the car has ran like crap. I drove it Monday/Tuesday, and it was fine. Wednesday and Friday it was a total dog. So rich it burned the eyes and would barely idle or drive at any speed.

I did a few runs with Datamaster and have some data if someone would like to see it. The EGR code is still there, but not too much else. The TPS was up around .67v, so I adjusted it to .55. The MAP sensor is reading between 40-55 at idle, which seems high, and explains why its in fuel cell 4 instead of 1 at idle. On Monday and Tuesday, everything seemed fine (not the smoothest idle like it used to, but perfectly driveable). Friday when it is running like garbage, the O2 mvolts were above 800 at idle (in closed loop), with no cross counts. Once I start driving a little it started bouncing above/below but still bogs big time. After this is also set a rich exhaust code (duh). BLMs also drop to around 108 frequently, and I think dropped into the 90's at some point.

I tested for vacuum leaks (soapy water, propane), and couldn't find anything. I also swapped the plugs again and no change. It sucks to drive and our emissions is due next month. I can't think of anything that wouldn't affect the car all of the time? Is there a way to test for a fuel injector hanging open? I tried to listen and they seemed fine. I'm thinking it must be something on the drivers side since the O2 sensor is seeing the rich condition?

PLEASE, any thoughts welcome.
(also posted in TPI, but I think it may be more fitting here)

SpitotRs305

have you replaced the coolant temp sensor?

Jeffrey Fontaine

No I haven't, but according to datamaster it is right on compared to my autometer gauge connected to the DS head. It's also staying in closed loop so I tended to rule that out.

Toehead

Your MAP is high for idle. Mine pulls it down to about 28.

Jeffrey Fontaine

That's what I think too, based on what I've read and what fuel trim cell its in. I wish I could find it, I've visually checked every vacuum hose I could find and tried soapy water and propane.

I think I'm going to pick up a new MAP tonight and see if that has any effect. Anything wrong with a regular parts store (Wells) variety?

RBob

iTrader: (1)

I would get a GM MAP sensor from a JY before using an aftermarket. I feel the same about ignition modules. But I don't think the issue is the MAP.

If you still have the original injectors (Multec), the symptoms sound like the injectors are on the way out. Can try ohm'ing them, but if they all ohm OK, it doesn't mean that they are OK. If you can do the resistance check while they are hot.

RBob.

Jeffrey Fontaine

I do still have the original injectors. Can you give more specifics on how to test them? I plan on ordering a Helms but haven't yet.

RBob

iTrader: (1)

Pull the electrical connectors on the injectors. Then measure between the two injector connector tangs for resistance, or ohms. Do this for each injector. Each one should be above 12 ohms, and ideally 16 - 17 ohms.

If any read under 12 ohms, then that injector is bad.

RBob.

P.S. to remove the connectors from the injectors. On the injector connector is a wire C clip. Push in on the top bow part on the clip and pull the connector off.

Jeffrey Fontaine

Well I checked them all last night, and they ranged from 15.2 - 17.6 ohms. So, kind of rules that out. While inspecting them I found that the hose to the PCV valve in the DS head had a slice, but replacing it had little to no effect.

I'm thinking the only thing left to test is the FPR? I have a pressure tester for vacuum etc but I'll have to buy the fitting to test pressure. Does anyone have a "how-to" on this? If that checks out I think I'll have to bring it to a mechanic so they can track down a vacuum leak...

PS - Thanks for the tip on injector connector removal

If anyone would like to see my Datamaster files let me know...

Jeffrey Fontaine

OK, TTT.

I finally got my AC Delco EGR valve and replaced that last night. Drove the car today and it is better, but not yet cured. Still have light throttle bog/surge, and idle is bouncy at best. At (closed loop) idle, mV's are pegged above 800. Since it smells rich, is reading rich, and spit out a code 45 rich exhaust, I think the 02 sensor is ok. Also, as said above, MAP readings seem high, but I can't find any leaks. Is there anything else that could cause this?

So far, we have the following:
TPI 305/auto, 138k - only mods are K&N's and an Edelbrock cat-back (and did a TB coolant bypass when I put it back together last night)
2 years and 8,000 miles ago I replaced plugs, wires, cap, rotor, O2 sensor, fule filter, and Cat converter.

In trying to diagnose the issue:
Replaced all 8 spark plugs
Checked for vacuum leaks, didn't find any
Checked EGR solenoid, tested good
Checked and replaced EGR valve (and cleaned passages)
Checked ohms on injectors, all checked ok
Checked vacuum line to FPR, no fuel
No apparent fuel in canister to TB line
Adjusted TPS to .57v at idle (was .62v)

I noticed today while looking at the datastream that the BLM's tend to trickle down from 128 to 88-91, then reset to 128 and back down again. One cycle takes about 6-10 seconds. I also noticed that the timing seems to go 20* before it jumps back to 128. Is it normal for timing to vary from 10-20* at idle?

I removed the connector for the MAP as suggested elsewhere to rule that out and it would put a fixed amount in the "formula". If it smoothed out, than it was the problem. Well, the car wouldn't even idle without it hooked up, is this normal?

The only thing left I can think of is to test that fuel pressure is holding. Idiot me put the car back together hoping the EGR would fix it, so I'll be ripped having to tear it apart again I can double check the timing, but I don't think this would be caused by that.

Thanks for any opinions.

Jeffrey Fontaine

Well, how long should the system hold pressure? W/ the pump on (engine off), it goes to about 40, when pump goes off, went to 38psi, and after about 30 mins was down to about 32. Tried it again and went to 43 w/ pump off, down to about 22 in 30 mins.

I'm pretty sure that's bad. Since I checked the vacuum line to the FPR and it didn't have fuel, I assume its at least one leaking injector?

Looks like I'll have to pull the plenum and runners again... Anyone have any 19lb injectors and/or AFPR they'd let go cheap? Next year I'm planning on swapping to an HSR so I'd prefer not to buy brand new stuff...

Jeffrey Fontaine

Well, just got done swapping the injectors. Come to find out the old ones weren't leaking (verified while attached to the rail but out of the manifold). I swapped them anyway since it was apart and they were Multecs. I also replaced the O2 sensor w/ a new AC to replace the Bosch, and replaced the original coil (138k!) w/ a new MSD unit.

I think it may run a wink better, but still not fixed. I have yet to be able to datalog because for some reason DataMaster sometimes gives my laptop the blue screen of death.

Does anyone else have any ideas? I think I have ruled out fuel but spark seems fine too. I haven't ohm'd the wires but I did pull them one at a time and all "changed" the idle...

I think tomorrow I'm going to call my trusted local mechanic, I'm out of ideas.

SpitotRs305

have you tried just replacing the MAP?

Jeffrey Fontaine

Yup, no difference.

FWIW, here are the emissions tests before the last round (injectors, O2 sensor, and coil):

HC 272 (limit 60)
CO 8.35 (limit .32)
NOx 377 (limit 700)

Here are the results from the test 2 years (and approx. 8k) ago, which was just after the tuneup mentioned in post #1.

HC 60
CO .04
NOx 515

Maybe that will help the smart people here

Jeffrey Fontaine

Replaced the cap/rotor, still getting code 45!!! AHHHHHHHHHHHHHHHHHHHHH.

Anyone have any ideas? I'm out of time, money, and ideas, so off to the mechanic it goes. I can feel it hurting already...