Pinging when hot
 

Anyone experience engine pinging when car gets hot?

My car runs great when cool. I can floor it and get great response and acceleration. Once car gets heat soaked (coolant temps are fine), I get pinging under hard acceleration.

I've set car to factory timing, running high octane fuel, new plugs, high flow fuel pump, oil cooler, wrapped headers.

Thoughts are:
1. Fuel is getting super heated and pre igniting
2. Heat is preventing distributor from doing its job( have a TFI relocation kit)
3. Hot fuel lines causing vapor lock

Thought I would ask around before I start making random adjustments.

do you have a wide band to measure afr?

No I do not, but I had a bung welded in when I did my previous dyno tunes. I will be re-tuning for my AFR heads really soon. My plan is to use a Moates Quarterhorse to data log and make adjustments as necessary. I will connect a wideband at the same time to track the issue. I also ordered a chip and will flash it to the new required parameters after all the data is logged and finalized. I will post results when finished.

This totally went away and allowed me to completely redo my timing map when I added a sealed airbox. Without the air box my MS2 was recording intake temps as high as 200 degrees at the filter. Sealing it off lowered it significantly and took away the pre detonation.

Next I'm moving from the iron GT40 heads I have now to a set of AFR's. I've read that the iron heads have a tendency to heat soak more than aluminum which further leads to detonation.

-Jason

Engine specs would help: Static compression, dynamic compression, quench.

Did you confirm timing? Hot and cold. Idle, load, and 2,500 rpm's.

I'm running an E303 cam with AFR 165 heads,24lbs injectors, 70mm throttle body, and tuned MAF with Cobra upper and lower intake. Block was redone to stock specs and I set it at stock timing. Not sure of compression numbers. I will mess with it more when I dyno tune it shortly and add a chip.

Jason-
I have been studying the box you fabricated around your intake. The idea of high intake temps was discussed, and I noticed your filter is shoved closer in to the headlight. I am using a shorter pipe and a square filter. I think I will find a decent cone filter to move up into the unused space and lengthen my intake tube. Then I will make a box to protect it from the engine bay hot air. I want to do this before I hit the dyno.

Question- Is there a correct distance to keep MAF from the filter or from the throttle body? Is centered best?

You can see mine in this picture:
Attachment 6572

Are you saying you are running 24lb injectors with no tuning done to the EEC? Although the mass air sensor is set to "fool" the EEC, compensating for the 24lb injectors, you will most likely be much better off with the tune.

I would have the car as hot and up to normal track day operating temps as possible while tuning it. They can tell you where/what needs attention during the process and possibly if there are problems, you can be much more focused on the actual problem.

Worst case is you have to take it back for another tune after correcting any identified problems. Be sure the MAP, air charge and coolant temp sensors are known good pieces.

I see the MAP sensor is sideways - starting to tilt upside down a bit. Factory wise they are typically always vertical with the vent/sensor tube facing down. I have no idea here what is inside or how the internals are protected, etc. but is it possible water or something got into it causing a problem?

Mike

Going in for my tune on Tues. I searched high and low for a filter that would fit into the small space behind headlight. My intake temps were too high and I needed to solve that before the tune.

Started basic template with cardboard. Used my kids play-doh to determine proper height.
Attachment 6565

Final template after adjusting using smooshed play-doh.
Attachment 6566

I will bend out some aluminum tomorrow.

Should be nice when done.

Jason

Final product:
https://www.v8miata.net/attachment.p...ine=1427074989
https://www.v8miata.net/attachment.p...ine=1427074989

I also took an old signal light and did some backyard modification. Cut out the back, but left room for the bulb to still connect. Then I sliced thin lines in the lens to allow air to pass through. Thin coat of black paint to smoke it out.
https://www.v8miata.net/attachment.p...ine=1427074989
https://www.v8miata.net/attachment.p...ine=1427074989
https://www.v8miata.net/attachment.p...ine=1427074989

This SHOULD solve my hot intake temps and the pinging when hot. SHOULD!!!!!!

Damn that is one of the slickest bits of fab work I have seen in a long time. Looks great man!

Airbox came out great. I think I would use some brake duct tubing for fresh air vs the slotted signal. Curious to hear the performance results.