Josh9096

Ok. Thanks for the help. It feels like it has gotten worse. Now when starting slow in first, it sounds and feels like it dropped a couple cylinders until I give it more gas. If I shift to second too early, it will do it then too until more gas is applied.

Injuneer

Have you checked the fuel pressure, out on the road, with the engine under load? Seems OK in power enrichment mode, but why does is lean out for a few seconds at idle? Both sides could be erratic fuel pressure, one side could be an injector. But you have both situations happening.

There's also a lot of drift up an down in the idle RPM. When the engine is warming up, it's surging up to 200 RPM above target idle speed. That can be a peculiarity of the cam surge, and how well the tuner was able to control it.

Who assembled the timing set? Could it be off by a tooth?

Do you have any lifter noise that comes and goes from tine to time?

Injuneer

A new member (GarageBuM) mentioned he had a similar problem, and it turned out to be a screw on the Opti rotor that fell out and was bouncing around in the cap. He asked if you used Loc-Tite when you installed the rotor?

Josh9096

My engine builder did it along with the engine but I'm guessing he didn't. I was going to take it apart this weekend and take a look at it. Don't want to but I think I have to.

Josh9096

So I got the opti apart. The rotor screws were not loc-tite but they were tight. the contact on the rotor looks dirty or corroded. Is that normal? And the case had some crud on the inside. See pics. Everything else looked good. I was hoping that was my issue 😣

Tr1ggger

I did a full tune up fuel pump fuel filter when it warms up it idles crazy when I stomp on it bogs out if I drive it like my grand would it's fine besides the hesitation in idle going up and down when it warms up please help it starts right up every time I turn key

Msd Optispark spark plug msd wires fuel filter throttle position sensor water pump K&N air box oil change battery I cut the cats off map sensor fuel pump fuel filter stuff I done already

Injuneer

Might want to add a signature so we know the year, etc. Not all years of the LT1 are identical.

https://www.camaroz28.com/forums/lt1...nature-879835/

Also better to start your own thread, rather than hijack someone else's. Gets too confusing when people are responding to two different topics.

Did you buy the MSD Opti recently? Most of the MSD's sold over the past year (maybe 2 years) or so have had problems with erratic idle, due to issues with the optical cam position module. Easy to track down with a data log of the PCM. I have provided proof of this to MSD through one of their employees on another LT1 site. Last feedback was that they have resolved the problem by changing their optical modules.

Have you scanned it for codes? Did you have either of these problems (bogging, erratic idle) BEFORE you did the "tune up"?

Tr1ggger

95 z28 a4 stock got my optispark 2 months ago from team c it was doing this when I bought the car it had a black opitpark didn't know how to start my own thread new to this stuff I changed all those parts to fix this problem the car has 118 on it og the ac works for crying out loud I'm stuck

Injuneer

Best thing to do is download Scan9495, get a 16-pin OBD-1 cable (recommendations in the link) and run a data log of the car from cold startup, idling through closed loop to reveal the erratic idle speed, and then street driving it under the same conditions that produce the bog.

Attach the data log to a post so I can download it, and take a look at it.

https://www.camaroz28.com/forums/com...95-lt1-874306/

The author of Scan9495 is a member here, and can help with any problems encountered with the install or operation. He does live in Florida, and is struggling with restoring his home, so can't guarantee that the response will be immediate.

Can't guarantee it will diagnose the problem, but it has helped a lot in the past. To repeat my earlier question, HAVE YOU EVER SCANNED IT FOR CODES?

To start a new thread, open the forum you want to post it in. At the top of the topic listing (just above the "Threads in Forum" solid red bar) for the forum is a "NEW THREAD" button.

Tr1ggger

Your very helpful I appreciate it it will give a code even if the check engine light not on it works cause I took the maf plug off and it came on I will buy the ob1 and do the data scanasap

Injuneer

There are some codes that do not turn on the SES light. But the codes are stored, like all codes that set, and can be picked up with a code scanner. The Scan9495 software will record codes.

In addition, it gives you a record of all the sensor readings, and the calculated PCM parameters like injector pulse width, spark advance, knock retard, commanded idle air counts, target idle RPM, etc. By looking for places where the symptoms show up, like idle surge, and looking at what info the PCM was receiving, and how it responded, it is often possible to identify the cause of the problem.

Josh9096

So......back to my issue. I changed the optispark out due to the corrosion and cracked cap. (It was cheaper to buy new than to replace the cap and rotor) The car still has the back fire under 2000 rpms. Im about ready to crush this thing. (not really...too much money invested) im still waiting to buy a fuel pressure gauge that can reach my windshield so i can see it while driving. I dont know what else it could be.

Injuneer

I really think a lot of it goes back to a poor build, questionable head porting, and a poor tune given the size of the cam. Tune could be as simple as not entering the correct offsets for the new injectors. "Tip in" problems with big cams I believe can be related to incorrect timing, failure to reset the "cell" boundaries to increase the number of cells used when MAP values are raised so high by the cam, and who knows what else.

I am not a tuner. I look at data logs to find the symptoms and possible source of problems. The further the "build" departs from stock, the harder it becomes, because I rely on empirical data from past reviews. The fact that the engine make very low HP would seem to be the first thing to attack. Checking the fuel pressure makes sense in that respect. But the stumbles require a bit more expertise than I possess. You need to have the tune looked at by someone who really knows what they are doing. And "good" LT1 tuners are getting hard to find.

Not saying I won’t continue to try and help, just pointing out that I can’t guarantee that I will get good results.