I replaced the O2 (Denso) and TPS (NOS AC) Friday, car really seemed to be running well over the weekend, made my 100 mile commute yesterday with it feeling peppy for once. Even the idle improved, more stable, but since has gotten slightly erratic again with the rich/sluggish response's return. This morning, the Check Engine light came on for the first time since owning the car. Read code, 45 which can be a number of things. I did inspect the fuel injector a few weeks back, had a nice fan pattern at idle and under throttle.

So far I have replaced:
Plug wires
Plugs
Dist cap
Rotor
Temp gauge
Temp sending gauge
Air filter
Fuel filter
O2
TPS
TBI rebuild kit (not yet installed)

I know some expressed concern with me replacing parts without testing system components. The car sat for 17 years, almost every part appears to be original, I am refreshing the entire car, short on time getting my motorcycle ready for the season so I can put the car in the garage, drop the cradle for the refresh. My thought is it will all need replacing, just finding the fine line of what is immediately needed to keep it efficient while I commute until the bike is ready so I can devote more time to it. I will test the fuel pressure by this weekend, ordering the adapter from Actron tomorrow.

I notice if holding the throttle at a light steady amount, I can feel a slight pulse/surge which seems to come and go, though none of the gauges show this. The MPG seems to be half of what it should be at this point, though at times it gets close to 30. This tells me with it being intermittent something is either failing or possibly a loose connection with the issue coming & going randomly like it is.

The PO replaced the fuel pump, dropped/cleaned the tank. Also had a mechanic look at it in January when I first bought it as it ran out of gas taking it home because at the time I had no clue the fuel sender was bad. He reported no visual issues, tested it and informed me it was a bad sender and that it was just empty.

So I am thinking fuel regulator, injector as it does act rich. Hopefully I can get some daylight tomorrow to inspect the plugs.
I still have to get to the bottom of the wobbling timing mark, certainly feels like I am dealing with multiple layered issues.

Odd thing is, the only codes I have received since resetting it when I first got it have been 22 and now 45. Are codes not always thrown when a component is bad?
So is it possible that whatever the issue is, it's something not read by the ECM, like the injector leaking or fuel regulator?

[This message has been edited by mckaymotoworks (edited 04-23-2014).]

Reset ECM last night, ran to the corner store, had a stumble on take off. First thought was low on gas, filled it up this morning, tank took 5.2 gallons at 152 miles on tripometer.
Stumble persisted for a few miles, then goes away. Car seems to run pretty well again, get half way on the 50 mile commute on the interstate, between 50-65 MPH feels flat again.

I then get on the off ramp, feels off line peppy again, all the way to work, it again feels fairly normal. Ordering the GM TBI adapter so I can check fuel pressure.
Something is intermittently changing, and I suspect fuel pressure too, as suggested previously.

Id be interested in the response to this problem as well. I have an 84 manual and have replaced all of the above items with the exception of the temp and tbi rebuild. All delco plugs, wires etc. And still have this surge issue but I have not had a code thrown in a long time. I would not call my issue so much ss a surge but almost like a loss of power in quick succession between normal and loss. Mostly when on the insterstate holding a steady speed going up an incline. Almost like an AC compressor cycling on and off. (note no ac in this car. My research on the forum has lead me to coin this event as "chuggling". OP when does this happen to you? At crusing speeds, or when you mash tge throttle? Also do you have an auto or stick? Not sure if it is relevant but you never know.

quote Originally posted by lurtz: Id be interested in the response to this problem as well. I have an 84 manual and have replaced all of the above items with the exception of the temp and tbi rebuild. All delco plugs, wires etc. And still have this surge issue but I have not had a code thrown in a long time. I would not call my issue so much ss a surge but almost like a loss of power in quick succession between normal and loss. Mostly when on the insterstate holding a steady speed going up an incline. Almost like an AC compressor cycling on and off. (note no ac in this car. My research on the forum has lead me to coin this event as "chuggling". OP when does this happen to you? At crusing speeds, or when you mash tge throttle? Also do you have an auto or stick? Not sure if it is relevant but you never know.

Sounds similar and yes my workshop manual coined it as "chuggling" too. Mine is an auto for now, cruising speeds above 50 feel flat, but my off line & below 50 feel much better with the TPS replaced.
But others have suggested to check fuel pressure, that would align with the erratic performance.

Possible plugged converter?

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1984 Indy Fiero

Reset ECM the other night, code has not returned. Car is running ok, at 150 miles, time to fill up, see if mileage is still consistent,
Bike is almost done, so I'll be taking the car down for a refresh replacing most of these components.

Picked up a Echlin MAP, fuel regulator kit on sale at NAPA online last night. Have the TBI kit, need to pick up new fuel injector
I'll do the fuel pressure test tomorrow, compression test before weekend.

If all that checks out, I'll drop the cradle in the coming weeks, put engine on stand, clean carbon, match ports, new head gasket, water pump, oil pump, alternator, camshaft gearing and the other sensors left.
Clean/coat fuel tank, repair sender, hoses/gaskets, replace fuel pump with Bosh or better. Install the 4 speed, blast/paint cradle, rear suspension, front suspension/steering.

[This message has been edited by mckaymotoworks (edited 04-24-2014).]

Confirmed MPG still at 28 yesterday, storm came in last night, temp was 61* with high humidity this morning and guess what returned, the sluggish response. Still no codes, looking at it through various threads & Ogre's detailed paragraph on the MAP, really suspect it.

I have the Echlin replacement, I'll install this evening. Also saw where the MAP accounts for timing, possible that's the cause of my wobbly timing mark?

Picking up the fuel pressure kit after work as well, I'll report back along with my compression readings.

Where can I find the hard plastic vacuum lines that fit into the rubber boots? NLA?

Sounds almost moisture related if it returned only after the humidity kicked back up? is it possible that a bad ground could be the culprit. These cars are very finicky when it comes to proper grounding.

quote Originally posted by lurtz: Sounds almost moisture related if it returned only after the humidity kicked back up? is it possible that a bad ground could be the culprit. These cars are very finicky when it comes to proper grounding.

I checked all of them last week, cleaned and reattached. The symptoms are almost dead on to what Ogre says on his MAP article.
With this low front that just came in and it feeling too rich. I'll know more tonight